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[Illustration]




SCIENTIFIC AMERICAN SUPPLEMENT NO. 598




NEW YORK, JUNE 18, 1887

Scientific American Supplement. Vol. XXIII, No. 598.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.


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TABLE OF CONTENTS.

I.    BOTANY.--The Brazil Nut.--The botanical position, appearance,
      etc., and general features of the tree and plant.--1 illustration.


II.   DECORATIVE ART.--Decoration.--The study of ornaments.--By
      Miss MARIE R. GARESCHE.--The principles of ornament and
      relations between nature and art; ancient and mediæval art
      contrasted.--1 illustration.


III.  ELECTRICITY.--Electric Registering Apparatus for Meteorological
      Instruments.--Grime's telemareograph described; an apparatus
      giving distant registrations of tidal phenomena.--2 illustrations.

      The Montaud Accumulator.--Full account of construction and
      power of this recent battery.--4 illustrations.


IV.   ENGINEERING.--Belt Joints.--A new cement, the "Hercules
      glue," and its adaptation for cementing belt joints.


V.    MINERALOGY.--Precious Stones of the United States.--A review
      of Mr. G.F. KUNZ'S recent report on this subject.


VI.   MISCELLANEOUS.--A Clinical Lesson at "La Salpetriere."--A
      portraiture picture by M. ANDRE BROUILLET, of a clinic.--2
      illustrations.

      Inauguration of the statue of Denis Papin.--The statue to Papin
      erected in Paris by popular subscription.--1 illustration.

      The Action of the Magnet in Hypnosis.--The nullity of the action
      of the magnet disclosed.

      To Find the Day of the Week for any Year.--A new method devised
      by Lewis Carroll.


VII.  NAVAL ENGINEERING.--Some Recent High Speed Twin
      Screws.--By E.A. LINNINGTON.--An important paper on the subject
      of screw propulsion.--6 illustrations.

      The Havre Maritime Exhibition.--Notes on the recently opened
      exhibition of ships and naval appliances at Havre.--1 illustration.

      The New German Corvette Greif.--A recent addition to the German
      fleet illustrated and described.--1 illustration.

      The Steamship Great Eastern.--A plea for the mammoth
      steamer.--Probabilities of her future usefulness.

      Twin Screw Torpedo Boat.--The new sea-going vessel built by
      Yarrow & Co. for the Italian government.--Her extraordinary
      speed.


VIII. ORDNANCE.--Our Coast Defenses.--An interesting summary
      by Gen. H.L. ABBOTT of our means for defending our coasts.

      The New Krupp Guns.--The dimensions of the largest guns in
      the world, now in process of construction at Essen.--2 illustrations.


IX.   PHYSICS.--Colors of Thin Plates.--Report of a recent lecture by
      Lord Rayleigh.


X.    TECHNOLOGY.--Recent Advances in Sewing Machines.--By
      JOHN W. URQUHART.--A recent lecture before the Society of
      Arts of London, giving an exhaustive review of the subject.--15
      illustrations.

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THE HAVRE MARITIME EXHIBITION.


The Havre Maritime Exhibition opened on the 7th of May.

Will this exhibition awaken general interest, or will it prove a local
affair simply? This is a secret of the weeks that are to follow.

Should nothing chance to discourage the general interest that surrounds
Havre, to dampen the enthusiasm of the public, or to act to the prejudice
of the exhibitors, whose very evident desire is to show nothing but
remarkable products in every line, the International Maritime Exhibition
will prove a great success.

[Illustration: THE INTERNATIONAL MARINE EXHIBITION AT HAVRE.--THE
PRINCIPAL ENTRANCE.]

The people of Havre have two points of comparison that more particularly
concern themselves: Their Maritime Exhibition of 1868, which, as far as
exhibition goes, was a complete success, is the first. The financial
results of it were not brilliant, but that was due to certain reasons upon
which it is not necessary to dwell. On the contrary, the Rouen Exhibition
of 1884 proved profitable.

The Havre Exhibition, under able management, can have only a like good
fortune. It must be said that the people of Havre would be deeply
humiliated should it prove otherwise.

A very appropriate location was selected for the Exhibition, in the busiest
quarter of the center of the city. Its circumference embraces one of the
finest docks of the port--the Commerce Dock, thus named because it could
not be finished (in 1827) except by the financial co-operation of the
shipowners and merchants of the city. For the purposes of the Exhibition,
this dock is now temporarily closed to navigation.

In the various structures, wood has been exclusively employed. The main
building, which alone has a monumental character, is Arabic in style, and
is situated in the center of Gambetta Place, over Paris Street, which here
becomes a tunnel. Two facades overlook the ends of this tunnel. A third
facade, which is much longer, fronts Commerce Dock.

The edifice is surmounted by a spherical cupola that serves as a base to a
semaphore provided with masts and rigging. On each side of the sphere there
are two pendent beacons. Wide glazed bays open in the external facades, and
allow the eye to wander to the south through Paris Street as far as to the
outer port, to the summits of Floride, and to see beyond this point the bay
of La Seine, Honfleur, and the coast of Grâce. To the north, the most
limited view has for perspective the City Hall, its garden, and the
charming coast of Ingonville.

The principal facade, that which fronts Commerce Dock, from which it is
separated solely by a garden laid out on Mâture Place, is the most
attractive and most ornamented. Here are located the restaurants, the
cafes, the music pavilion, and a few other light structures.

Internally, this portion of the Exhibition comprises a vast entertainment
hall, brilliantly and artistically decorated with tympans representing the
three principal ports of commerce--Havre, Bordeaux, and Marseilles--and
with pictures by the best marine painters. It is lighted by an immense
stained glass window which fronts Commerce Dock and the garden, and which
lets in a flood of soft light.

The galleries to the right and left, over Paris Street, are reserved for
the exhibitions of the ministers of state and of the large public
departments, and for models, specimens, plans, and drawings of war and
merchant vessels, and of pleasure boats, and for plans of port, roadstead,
and river works.

Two endless galleries run to the north and south of Commerce Dock, parallel
with Orleans Wharf on the one hand and Lamblardie Wharf on the other.

The northern gallery is connected by a foot bridge with the annex of
Commerce Place, where is located the colonial exhibition, the center of
which is occupied by a Cambodian pavilion, in which are brought together
the products of Indo-China and Algeria. For half of their extent, the two
galleries are separated from the dock by a promenade provided with seats
and covered with a roof. On this promenade, it became necessary to make
room for certain belated exhibitors whose products are not affected by the
open air.

In Commerce Dock are to be seen, floating, specimens of every ancient and
modern naval construction, French and foreign, among which are the state
convette Favorite and an English three-master converted into a cafe boat.
We find here, too, the giant and prehistoric oak of the Rhine, on board of
the Drysphore.

Commerce Dock is divided into two parts by a foot bridge, which allows the
visitors to pass from one side to the other without being compelled to
tiresomely retrace their steps.

The main entrance to the Exhibition is opposite the portico of the theater,
on Gambetta Place. A second entrance is found on Commerce Place in the
colonies annex. The others, near the center, are on Orleans Wharf, opposite
Edward Larue Street, and on Lamblardie Wharf, opposite Hospital Street and
opposite Saint Louis Street.

The garden of the Exhibition and the galleries that surround it are
illuminated at night by the electric light.--_L'Illustration._

       *       *       *       *       *




OUR COAST DEFENSES.


General H.L. Abbott delivered a lecture before the Academy of Sciences in
New York, on the evening of March 21, a summary of which is given by the
_Herald_ as follows:

According to General Abbott, the country needs for its coast defenses:

    Heavy guns;
    Armor-clad casemates;
    Disappearing gun carriages in earthworks;
    Heavy mortars;
    Submarine mines or fixed torpedoes; and
    Fish torpedoes.

The lecturer said that this nation may be attacked in four ways: First, by
fleet and army combined, as in our revolutionary war; second, by blockading
the entrances to all our ports; third, by bombardment of our seaport cities
from a long distance; fourth, by a fleet forcing its way into our harbors,
and making a direct attack or levying tribute on our people.

The first is not now greatly to be feared. We are too distant from great
powers, and too strong on land.

The second should be met by the navy, and is, therefore, outside a
discussion of coast defenses.

The third is not probable, though it may be possible. The extreme range of
10 miles for heavy guns cannot be obtained from shipboard, and as an
elevation of only 15° or 16° can be given, not over 5 to 6 miles range is
attainable.

The fourth is the one which is possible, probable, even certain--if we have
war before we have better defenses.

The race between guns and armor began about thirty years ago, and there has
been more development in ships and guns in that time than in the two
hundred preceding years. The jump has been from the 7 in. rifle as the
largest piece to the 110 ton Armstrong; in armor, from 4½ in. of iron to
the Inflexible with 22 in. of steel plating. The new Armstrong gun of 110
tons, tried only recently, with 850 pounds of powder and an 1,800 pound
shot can pierce all the targets, and so far guns have the victory over
armor. This gun developed 57,000 foot tons of energy, and will probably
reach 62,000. Imagine the Egyptian needle in Central Park, shod on its apex
with hard steel, dropped point downward from the height of Trinity steeple;
it weighs 225 tons, and it would strike with just about the effect of one
of the 110 ton gun's projectiles. Two of these guns are ready for the
ironclad Benbow, and the Italians have several equally powerful of 119 tons
from Herr Krupp. The most powerful gun in the United States, the 15 in. or
the 12 in. rifle, has a muzzle energy of 3,800 foot tons.

Ships like the Inflexible are the most powerful afloat. A steel water-tight
deck extends across the ship, and she has 135 water-tight compartments. Her
guns and engines amidships have a protection of 24 in. of armor, and
amidships she has a citadel carrying two revolving turrets, each containing
two 80 ton guns. Her turret armor is 18 in. thick. She can make 14 knots,
and she has cost $3,500,000. But she has a low freeboard, and the guns,
therefore, get no plunging fire.

The French ship Meta has her heaviest guns mounted _en barbette_, high
above the water line, giving a splendid plunging fire.

Either of these ships could enter any of our harbors and hold us at her
mercy.

The entrance to the harbor of Alexandria, Egypt, is about 5 miles across.
At the time of the bombardment the protecting fortifications were situated
at the east end, in the center, and at the west end. On the west there were
mounted 20 modern guns of great size and power, and there were 7 others at
the east end.

Although the Egyptians fought bravely, they did very little harm to the
English fleet, while on the second day the defense was silenced altogether.
Following the bombardment--as in Paris--came the reign of mob law, doing
more harm than the shells had done; and it is a possibility that every such
bombardment would be followed by such an overthrow--at least temporary--of
all forms of law and order.

The ships that had silenced the Alexandria batteries--which had 27 heavy
guns more than we have--could reach our coasts in 10 or 12 days, and we
would have nothing to meet them.

Armor-clad casemates are beginning to take the place of masonry. A
tremendous thickness of masonry is built up to the very embrasures for the
guns in the steel-clad turrets. This (the Gruson) system has been adopted
by Belgium, Holland, Germany, Austria, and Italy.

In 1882 England had 434 heavy modern guns behind armored shore batteries;
besides these at home, she had 92 in her colonies, of which 13 were in
Halifax and 11 in Bermuda--for our express benefit.

What we have are brick and stone casemates and earthworks. A sample granite
casemate, with iron-lined embrasure, was built at Fortress Monroe, and 8
shots were fired at it from a 12 in. rifle converted from an old 15 in.
smooth bore. This gun develops only 3,800 foot tons of energy--a mere
nothing compared with the 62,000 foot tons of the English and German 110
ton guns.

General Abbott showed most conclusive proof of the worthlessness of masonry
forts in pictures showing the effect of the shots. The massive 8 feet
thickness of granite was pierced and battered till it looked like a ruin.
Not a man inside would have been left alive.

He also showed a "disappearing" gun in an earthwork, the gun recoiling
below the level of the parapet and being run up to a firing position by a
counterweight. In 1878 Congress stopped all appropriations for defenses,
and nothing had been done since.

General Abbott said that we needed submarine mines or fixed torpedoes,
which should be thickly interspersed about the channel and be exploded by
an electric battery on shore. To prevent these torpedoes from being
exploded by the enemy, the surface over them should be covered by plenty of
guns. Heavy guns and mortars were needed to resist attacks by heavy
iron-clads. Movable torpedoes were valuable, but only as an auxiliary--a
very minor auxiliary--compared with submarine mines. We should be cautious
not to infer that torpedoes made a satisfactory defense alone, as they must
be protected by large and small guns, and they form only a part of the
chain of general defenses.

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THE STEAMSHIP GREAT EASTERN.

[Footnote: See Engraving in SUPPLEMENT NO. 584.]


The history of the Great Eastern is full of surprises. It is always that
which is most unlikely to happen to her which occurs. Not long since we
recorded her sale by auction in Liverpool for £26,000. It was stated that
her purchasers were going to fit her out for the Australian trade, and that
she would at once be sent from Dublin to Glasgow to be fitted with new
engines and boilers, and to undergo thorough renovation. Lord Ravensworth,
in his address to the Institution of Naval Architects, spoke recently of
the bright future before her in that Australian trade for which she was
specially built. Yet at this moment the Great Eastern is lying in her old
berth in the Sloyne at Liverpool, and unless something else at present
quite unforeseen takes place, she will once more play the undignified part
of a floating music hall. It seems that although she was certainly sold, as
we have stated, the transaction was not completed. Her owners then cast
about for the next highest bidder, who at once took her. He is, we
understand, a Manchester cotton spinner, and he paid £25,500 for her. It is
no secret that Messrs. Lewis made a considerable sum out of the ship last
year, and the knowledge of this fact has no doubt induced her present owner
to follow their example. The ship left Dublin on Sunday, April 3, under her
own steam and in tow of two Liverpool tugs, the Brilliant Star and the
Wrestler, and arrived in the Mersey without accident on Monday, after a
passage of only thirteen hours. Mr. Reeves, formerly her chief officer, has
been made captain. Mr. Jackson is still chief engineer. We cannot at
present explain the fact that she went more than twice as fast as she has
done recently, her engines making as many as 36 revolutions a minute, save
on the assumption that while lying at Dublin much of the enormous growth of
seaweed on her bottom died off, as will sometimes happen as a result of
change of water. Her engines and boilers, too, have had a good overhaul by
Mr. Jackson, and this may account in part for this improvement. It is much
to be regretted that the scheme of using the ship for her legitimate
purpose has not been carried out. It is not, however, yet too late. The
Great Eastern was not a success in Dublin, for one reason, that a beer and
spirit license could not be obtained for her. It is said that notice has
been given at the Birkenhead police court that any application for a
license of a similar kind will be opposed. Whether the ship will be as
popular a resort without as she was with a license, we cannot pretend to
say; and we may add that all our predilections are against her degradation
to the status of a floating music hall. The greater her failure as such,
the greater the chance of her being put to a better use; and it may help to
that desirable end if we say here something concerning the way in which she
could be rendered a commercial success as a trader.

It may be taken as proved that the present value of the ship is about
£26,000. Mr. De Mattos gave, we understand, £27,000 for her, and he bought
her by auction. The last sale gives nearly the same figures. If we assume
that there are 10,000 tons of iron in her, we may also assume that if
broken up it would not fetch more than £3 a ton at present rates; but even
if we say £4, we have as a total but £40,000. To break the ship up would be
a herculean task; we very much doubt if it could be done for the difference
between £26,000 and £40,000; her engines would only sell for old iron,
being entirely worthless for any other place than the foundry once they
were taken out of her; as for her boilers, the less said about them the
better. In one word, she would not pay to break up. On the other hand, by a
comparatively moderate further outlay, she might be made the finest trading
ship afloat. There are two harbors at all events into which she can always
get, namely, Milford and Sydney. There are others, of course, but these
will do; and the ship could trade between these two ports. By taking out
her paddle engines, she would be relieved of a weight of 850 tons. The
removal of her paddle engine boilers would further lighten her, and would
give in addition an enormous stowage space. By using her both as a cargo
and a passenger ship, the whole of the upper portion could be utilized for
emigrants, let us say, and the lower decks for cargo, of which she could
carry nearly, if not quite, 20,000 tons. She would possess the great
advantage that, notwithstanding she was a cargo ship, she would be nearly,
if not quite, as fast as any, save a few of the most recent additions to
the Australian fleet. There is every reason to believe that she has been
driven at 14 knots by about 6,000 horse power. We are inclined to think
that the power has been overstated, and we have it on good authority that
she has more than once attained a speed of 15 knots. Let us assume,
however, that her speed is to be 13 knots, or about fifteen miles an hour.
Assuming the power required to vary as the cube of the speed, if 6,000
horsepower gave 14 knots, then about 4,800 would give 13 knots--say 5,000
horse power. Now, good compound engines of this power ought not to burn
more than 2 lb. per horse per hour, or say 4.5 tons per hour, or 108 tons a
day. Allowing the trip to Australia to take forty days, we have 4,320 tons
of coal--say 5,000 tons for the trip. The Etruria burns about this quantity
in the run to New York and back. For each ton of coal burned in the Great
Eastern about 15,000 tons of cargo and 3,000 passengers could be moved
about 3-1/3 miles. There is, we need hardly say, nothing afloat which can
compare in economy of fuel with this. Taken on another basis, we may
compare her with an ordinary cargo boat. In such a vessel about 3,000 tons
of grain can be moved at 9 knots an hour for 600 horse power--that is 5
tons of cargo per horse power. Reducing the speed of the Great Eastern to 9
knots and about 2,000 horse power, we have 9 tons of cargo moved at 9 knots
per horse power; so that in the relation of coal burned to cargo moved she
would be nearly twice as economical as any other vessel afloat.

The important question is, What would the necessary alterations cost? Much,
of course, would depend on what was done. A very large part of the present
screw engines could be used. For example, the crank shaft, some 2 feet in
diameter, is a splendid job, and no difficulty need be met with in working
in nearly the whole of the present framing. If the engines were only to be
compound, two of the existing cylinders might be left where they are, two
high-pressure cylinders being substituted for the others. If triple
expansion were adopted, then new engines would be wanted, but the present
crank and screw shafts would answer perfectly. The present screw would have
to be removed and one of smaller diameter and less pitch put in its place.
All things considered, we believe that for about £75,000 the Great Eastern
could be entirely renovated and remodeled inside. Her owners would then
have for, say, £100,000 a ship without a rival. Her freights might be cut
so low that she would always have cargo enough, and her speed and moderate
fares ought to attract plenty of passengers. Sum up the matter how we may,
there appears to be a good case for further investigation and inquiry as to
the prospects of success for such a ship in the Australian trade, and the
opinion of merchants and others in Melbourne and Sydney ought to be
obtained. Something would be gained even if the opinions of unprejudiced
experts were adverse. We might then rest content to regard the ship as an
utter failure, and not object to see her sunk and filled with concrete to
play the part of a breakwater. Until, however, such an opinion has been
expressed after full discussion, we must continue to regard the ship as fit
for something better than a music hall and dancing saloon.--_The Engineer_.

       *       *       *       *       *




THE NEW GERMAN CORVETTE GREIF.


Our cut represents the corvette Greif--the latest addition to the German
fleet--on its trial trip, March 10. As other naval powers, especially
England and France, have lately built corvettes and cruisers which can
travel from 17 to 18 knots, while the fastest German boats, Blitz and
Pfeil, can make only 16 knots an hour, the chief of the Imperial Admiralty
decided to construct a corvette which should be the fastest vessel in the
world. The order was given to the ship and engine corporation "Germania,"
of Berlin and Keil, in April, 1885, the requirements being that the engines
should generate 5,400 h.p., and that the vessel, when loaded, should have a
speed of 19 knots, a point which has never been reached by any boat of its
size. The hull is made of the best German steel of Krupp's manufacture, and
measures 318 ft. in length at the water line, with a breadth of beam of 33
ft., the depth from keel to deck being 22 ft. It draws about 11 ft., and
has a displacement of 2,000 tons.

As the vessel is to be used principally as a dispatch boat and for
reconnoitering, and as--on account of its great speed--it will not be
obliged to come into conflict with larger and stronger men-of-war, no great
preparations for protection were needed, nor was it necessary that it
should be heavily armed, all available room being devoted to the engines,
boilers, and the storing of coal; these occupy more than half the length of
the vessel, leaving only space enough for the accommodation of the officers
and crew at the ends. The armament consists of five Hotchkiss revolving
guns on each side, and a 4 in. gun at each end, the latter being so
arranged that each one can sweep half the horizon.

The keel was laid in August, 1885, and the ship was launched July 29,
1886, on which occasion it was christened Greif. On the trial trip it was
found that the slender shape of the vessel adapted it for the development
of a very high rate of speed under favorable conditions, when it can make
at least 22 knots an hour, so that the speed of 19 knots an hour guaranteed
by the builders can certainly be reached, even when traveling at a
disadvantage. In spite of its great length, the Greif can be easily
maneuvered. When moving forward at full speed, it can be made to describe a
circle by proper manipulation of the rudder, and by turning one screw
forward and the other backward, the ship can be turned in a channel of its
own length.

[Illustration: THE NEW GERMAN WAR STEAMER GREIF.]

A large and rapid cruiser, also for the German navy, is being built by the
corporation "Germania". This vessel is of about the same length as the
Greif, has more than double its displacement, and will make 18 knots an
hour, an unusual rate of speed for a vessel of its class. It will be
launched by the last of the summer or early in the fall.

       *       *       *       *       *




TWIN SCREW TORPEDO BOAT.


We give several illustrations of a sea going twin screw torpedo boat lately
built for the Italian government by Messrs. Yarrow & Co., of Poplar. The
vessel in question is 140 ft. long by 14 ft. wide, and her displacement
approaches close on 100 tons. The engines are of the compound surface
condensing type ordinarily fitted by this firm in their torpedo boats,
excepting where triple compounds are fitted. The general arrangement is
shown by the sectional plan. As will be noticed, there are two boilers, one
before and the other aft of the engines, and either boiler is arranged to
supply either or both the engines. Yarrow's patent water tight ash pans are
fitted to each boiler, to prevent the fire being extinguished by a sudden
influx of water into the stokehold. There is an independent centrifugal
pumping engine arranged to take its suction from any compartment of the
boat. There are also steam ejectors and hand pumps to each compartment.
These compartments are very numerous, as the space is much subdivided, both
from considerations of strength and safety. Bow and stern rudders are
fitted, each having independent steam steering gear, but both rudders can
be worked in unison, or they can be immediately changed to hand gear when
necessary. The accommodation is very good for a vessel of this class.
Officers' and petty officers' cabins are aft, while the crew is berthed
forward.

[Illustration: TWIN SCREW TORPEDO BOAT FOR THE ITALIAN GOVERNMENT.]

The armament consists of two bow tubes built in the boat. There are two
turntables, as shown in the illustrations, each fitted with two torpedo
tubes. These, it will be noticed, are not arranged parallel to each other,
but lie at a small angle, so that if both torpedoes are ejected at once,
they will take a somewhat divergent course. Messrs. Yarrow have introduced
this plan in order to give a better chance for one of the torpedoes to hit
the vessel attacked. There are two quick firing three pounder guns on deck,
and there is a powerful search light, the dynamo and engine being placed in
the galley compartment.

We believe, says _Engineering_, this torpedo boat, together with a sister
vessel, built also for the Italian government, are the fastest vessels of
their class yet tried, and it is certain that the British Navy does not yet
possess a craft to equal them. It is an extraordinary and lamentable fact
that Great Britain, which claims to be the foremost naval power in the
world, has always been behind the times in the matter of torpedo boats.

The official trial of this boat was recently made in the Lower Hope in
rough weather. The following is a copy of the official record of the six
runs on the measured mile:

    Boiler   | Receiver |         |Revolutions |       |       |Second
    Pressure.| Pressure.| Vacuum. | per Minute.| Speed.| Means.| Means.
-------------+----------+---------+------------+-------+-------+------
      |lb.   |     lb.  |    in.  |            |       |       |
1     | 130  |      32  |     28  |    373     | 22.641|       |
      |      |          |         |            |       | 24.956|
2     | 130  |      32  |     28  |    372.7   | 27.272|       | 24.992
      |      |          |         |            |       | 25.028|
3     | 130  |      32  |     28  |    372     | 22.784|       | 25.028
      |      |          |         |            |       | 25.028|
4     | 130  |      32  |     28  |    377     | 27.272|       | 25.138
      |      |          |         |            |       | 25.248|
5     | 130  |      32  |     28  |    375     | 23.225|       | 25.248
      |      |          |         |            |       | 25.248|
6     | 130  |      32  |     28  |    377     | 27.272|       |
      +------+----------+---------+------------+-------+-------+-------
Means.| 130  |      32  |     28  |    274½    |       |       | 25.101
             |          |         |            |       |       | knots
-------------+----------+---------+------------+-------+-------+-------

--_Engineering_.

       *       *       *       *       *




SOME RECENT HIGH-SPEED TWIN SCREWS.

[Footnote: A paper recently read before the Institution of Naval
Architects, London.]

By E.A. LINNINGTON.


One of the most interesting and valuable features in the development of
naval construction in recent years is the great advance which has been made
in the speeds of our war ships. This advance has been general, and not
confined to any particular vessel or class of vessel. From the first class
armored fighting ship of about 10,000 tons displacement down to the
comparatively diminutive cruiser of 1,500 tons, the very desirable quality
of a high speed has been provided.

These are all twin screw ships, and each of the twins is driven by its own
set of engines and line of shafting, so that the propelling machinery of
each ship is duplicated throughout. The speeds attained indicate a high
efficiency with the twin screws. In all ships, but more especially in high
speed ships, success depends largely upon the provision of propellers
suited for the work they have to perform, and where a high propulsive
efficiency has been secured, there is no doubt the screws are working with
a high efficiency. The principal purpose of this paper is to record the
particulars of the propellers, and the results of the trials of several of
these high speed twin screw ships. The table gives the leading particulars
of several classes of ships, the particulars of the screws, and the results
obtained on the measured mile trials from a ship of each class, except C.
The vessels whose trials are inserted in the table have not been selected
as showing the highest speeds for the several classes. Excepting C, they
are the ships which have been run on the measured mile at or near the
designed load water line. On light draught trials, speeds have been
attained from half a knot to a knot higher than those here recorded. No
ship of the class C has yet been officially tried on the measured mile, but
as several are in a forward state, perhaps the actual data from one of them
may shortly be obtained. All these measured mile trials were made under the
usual Admiralty conditions, that is to say, the ships' bottoms and the
screws were clean, and the force of the wind and state of the sea were not
such as to make the trials useless for purposes of comparison. On such
trials the i.h.p. is obtained from diagrams taken while the ship is on the
mile, and the revolutions are recorded by ruechanical counters for the time
occupied in running the mile. Not less than four runs are made during a
trial extending over several hours. The i.h.p. in the table is not
necessarily the maximum during the trial, for the average while on the mile
is sometimes a little below the average for the whole of the trial. The
revolutions are the mean for the two sets of engines, and the i.h.p. is the
sum of the powers of the two sets. The pitch of the screw is measured. The
bolt holes in the blade flanges allow an adjustment of pitch, but in each
case the blades were set as nearly as possible at the pitch at which they
were cast. The particulars given in the table may be taken to be as
reliable and accurate as such things can be obtained, and for each ship
there are corresponding data; that is, the powers, speeds, displacements,
revolutions, pitches, and other items existed at the same time. There are a
few points of detail about these propellers which deserve a passing notice.
In Fig. 1 is shown a fore and aft section through the boss. It will be
observed that the flanges of the blades are sunk into the boss, and that
the bolts are sunk into the flanges. The recess for the bolt heads is
covered with a thin plate having the curve of the flange, so that the
flanges and the boss form a section of a sphere. This method of
construction is a little more expensive than exposed flanges and bolts,
which, however, render the boss a huge churn. With the high revolutions at
which these screws work, a spherical boss is extremely desirable, but, of
course, the details need not be exactly as shown in the illustration. The
conical tail is fitted to prevent loss with eddies behind the flat end of
the boss, and is particularly valuable with the screws of high speed ships.
The light hood shown on the stern bracket is for the purpose of preventing
eddies behind the boss of the stern bracket, and to save the resistance of
the flat face of the screw boss. The edges of the blades are cast sharp,
instead of being rounded at the back, with a small radius, as in the usual
practice--the object of the sharp edge being the diminution of the edge
resistance. The driving key extends the whole length of the boss, and the
tapered shaft fits throughout its length.

[Illustration: FIG. 1.]

These points of detail have been features of all Admiralty screws for some
years.

The frictional resistance of screw propellers is always a fruitful source
of inefficiency. With a given screw, the loss due to friction may be taken
to vary approximately as the square of the speed. This is not to say that
the frictional resistance is greater in proportion to the thrust at high
than at low speeds. The blades of screws for any speed should be as smooth
and clean as possible, but for high speed screws the absolute saving of
friction may be considerable with an improvement of the surface. There is
no permanent advantage in polishing the blades. No doubt there is some
advantage for a little time, and, probably, better results may thereby be
secured on trial, but the blades soon become rough, and shell fish and weed
appear to grow as rapidly on recently polished blades as on an ordinary
surface. These screws are of gun metal. They were fitted to the ships in
the condition in which they left the foundry. It appears that within
certain limits mere shape of blade does not affect the efficiency of the
screw, but, with a given number of blades and a given disk, the possible
variations in the form or distribution of a given area are such that
different results may be realized. The shapes of the blades of these
propellers are shown in Figs. 2, 3, and 4. It will be seen the shapes are
not exactly the same for all the screws, but the differences do not call
for much remark.

[Illustration: FIG. 2., FIG. 3. & FIG. 4.]

Fig. 2 shows the blades for the A screw. C and D have the same form. Fig. 3
shows in full lines the blades of the B screw, and, though very narrow at
the tips, they, like A, are after the Griffith pattern. The blades of E and
F are of a similar shape, as shown in Fig. 4, and approach an oval form
rather than the Griffith pattern. The particulars of these propellers would
be considered incomplete without some reference to their positions with
respect to the hulls. When deciding the positions of twin screws, there is
room for variation, vertically, longitudinally, and transversely. For these
screws, the immersions inserted in the table give the vertical positions.
The immersion in A is 9 ft., showing what may be done in a deep draught
ship with a small screw. Whatever the value of deep immersion may be in
smooth water, there can be no question that it is much enhanced in a
seaway. The longitudinal positions are such that the center of the screw is
about one-fifth of the diameter forward of the aft side of the rudder post.
The positions may, perhaps, differ somewhat from this rule without
appreciably affecting the performance, but, if any alteration be made, it
would probably be better to put the screws a little farther aft rather than
forward. The forward edges of the blades are from 2 ft. to 3 ft. clear of
the legs of the bracket which carries the after bearing. The transverse
positions are decided, to some extent, by the distance between the center
lines of the engines. As regards propulsive efficiency, it would appear
that the nearer the screws are to the middle line, the less is the
resistance due to the shaft tubes and brackets, and the greater is the gain
from the wake in the screw efficiency, but, on the other hand, the greater
is the augment of the ship's resistance, due to the action of the screws.
Further, the nearer the screws are to the hull, the less are they exposed.
But experience is not wanting to show that the vibration may be troublesome
when the blades come within a few inches of the hull. The average of the
clearances between the tips of the blades and the respective hulls is about
one-eighth of the diameter of the screw.

An interesting and noteworthy fact in connection with these propellers is
the wide differences in the pitches and revolutions, though the products of
the two do not greatly vary. Such differences are extremely rare in the
mercantile marine for similar speeds, but in war ships they are inseparable
from the conditions of the engine design. As a general rule, with
(revolutions × pitch) a constant, an increase of revolutions and the
consequent decrease of pitch allow a diminution of disk and of blade
area--other modifying conditions, such as the thrust, slip, number, and
pattern of blades, being the same. The screws for E and F are interesting,
because, with practically the same speeds and slips, there is a
considerable difference in the revolutions. It will be observed that F is a
vessel of finer form and a little less displacement than E, and, therefore,
has less resistance. Although E has the greater resistance and the screw
the smaller pitch/diameter, the higher revolutions permit the use of a
smaller screw. But from this example the influence of the high revolutions
in diminishing the size of screw does not appear so great as some empirical
rules would indicate. The screws for A and B are also worthy of attention.
Although the ship A has a much greater resistance than B, the screw of the
former is much the smaller, both in the blade area and the disk. A's
screws, however, in addition to 22 per cent. more revolutions than B, have
a much larger slip, and the blades have rather a fuller form at the tips.
Compared with the practice in the mercantile marine, the revolutions of
these screws are very high, and from the foregoing remarks it may appear
that much larger screws would be required for a merchant ship than for a
war ship of the same displacement and speed. There would, however, be
several items favorable to the use of small screws. For a given
displacement the resistance would be less in the mercantile ship, and with
the lower revolutions the proportion of blade area to the disk could be
increased without impairing the efficiency. Thus in passing from the war
vessel to a merchant ship of the same displacement, there are the lower
revolutions favorable to a larger screw, but, on the other hand, the
smaller resistance, larger proportion of blade area, and the coarser pitch,
are favorable to a diminution of the screw. The ship B has a very large
screw at 88 revolutions, but the tips are very narrow. If the blade were as
dotted for a diameter of 16 ft., the same work could be done with the same
revolutions, but with a little coarser pitch and a little more slip.

There is something to be said for large screws with a small proportion of
blade area to disk. For instance, two bladed screws have frequently given
better results than four bladed screws of smaller diameter, neglecting, of
course, the question of vibrations. Twin screws, however, should, as a
rule, be made as small as possible in diameter without loss of efficiency.
The advantages of small twin screws are the shorter shaft tubes and stern
brackets, deeper immersion, and less exposure as compared with large
screws. The exposure of the screws is usually considered an objection, but,
perhaps, too much has been made of it, for those well qualified to speak on
the subject consider that careful handling of the ship would, in most
cases, prevent damage to the screws, and that where the exposure is
unusually great, effectual protection by portable protectors presents no
insuperable difficulty.

                    HIGH SPEED TWIN SCREWS.
---------------------------------------------------------------------
                    |Ship A.|Ship B.|Ship C.|Ship D.|Ship E.|Ship F.
---------------------------------------------------------------------
Length, ft.         |  325  |  315  |  300  |  300  |  220  |  250
Breadth, ft.        |   68  |   61  |   56  |   46  |   34  |   32½
                    |       |       |       |       |       |
Draught on trial,   | 26 ft | 24 ft |       | 15 ft | 12 ft | 13 ft
  forward.          |  2 in |  6 in | ....  |  6 in | 10 in |  1 in
                    |       |       |       |       |       |
Draught on trial,   | 27 ft | 25 ft |       | 19 ft | 15 ft | 14 ft
  aft.              |  3 in |  6 in | ....  |  9 in |  2 in |  7 in
Displacement,       |       |       |       |       |       |
  tons.             | 9,690 | 7,645 | 5,000 | 3,584 | 1,560 | 1,544
I.M.S., sq. ft.     | 1,560 | 1,287 | 1,000 |   744 |   438 |   392
Speed of ship,      |       |       |       |       |       |
 knots.             | 16.92 | 17.21 | 18.75 | 18.18 | 16.91 |    17
I.H.P.              |11,610 |10,180 | 8,500 | 6,160 | 3,115 | 3,045
Revolutions per     |       |       |       |       |       |
 minute.            | 107.2 |   88  |  120  | 122.6 | 150.4 | 132.1
                    |       |       |       |       |       |
Pitch of            | 19 ft | 22 ft | 18 ft | 17 ft | 12 ft | 14 ft
 screw.             |  5 in |       |  9 in |  6 in |  7½in |  9 in
                    |       |       |       |       |       |
Slip. per cent      |  17.6 |  10   |  ...  |  14.2 |  9.7  |  11.4
                    |       |       |       |       |       |
Diameter of         | 15 ft | 18 ft | 14 ft | 13 ft | 10 ft | 11 ft
  screw.            |  6 in |       |  6 in |       |  6 in |
                    |       |       |       |       |       |
Diameter of         |  4 ft |  4 ft |  3 ft |  3 ft |  2 ft |  2 ft
  boss.             |  4 in | 11 in |  9 in |  5 in |  9 in | 10 in
Number of blades    |   4   |   4   |   3   |   3   |   3   |   3
Blade area of one   |       |       |       |       |       |
 screw.             |   72  |   87  |   60  |   47  |   24  |   24
Shape of blade.     |Fig. 2.|Fig. 3.|Fig. 2.|Fig. 2.|Fig. 4.|Fig. 4
 Pitch              |       |       |       |       |       |
----------          |  1.25 |  1.22 |  1.3  |  1.34 |  1.2  |  1.34
Diameter            |       |       |       |       |       |
  Disk              |       |       |       |       |       |
--------            |  2.62 |  2.92 |  2.75 |  2.82 |  3.6  |  3.96
Blade area          |       |       |       |       |       |
Immersion of        |  9 ft |  5 ft |       |  4 ft |  2 ft |  1 ft
  screw.            |       |  3 in | ....  |  4 in |  9 in | 10 in
--------------------------------------------------------------------

The slips of these screws vary from 10 to 17½ per cent., which is certainly
not an extensive range, considering the widely different working
conditions. Slip, as an indication of the efficiency of the screw, is not
only an interesting subject, but it is often one of importance. In these
ships, however, there is nothing about the slips which would give rise to
any doubts as to the fitness of the screws for their work.

[Illustration: FIG. 5. & FIG. 6.]

The ancient fallacy that small slip meant a high screw efficiency was
supported by the great authority of the late Professor Rankine. Experience
proved that considerable slips and efficient screws were companions. The
late Mr. Froude offered an explanation of this general rule in a paper read
before this Institution in 1878, and gave a curve of efficiency with
varying true slip. In Mr. R E. Froude's paper last year there was a form of
this curve, with an arbitrary abscissa scale for the slip, devised to
illustrate in one diagram the wide conditions covered by his experiments.
In the screws now under consideration, the values of the pitch/diameter
vary only from 1.2 to 1.34, and for these the abscissa values for the same
slips do not differ much. Taking the mean value, and bringing the slips to
a common scale, Fig. 5 is obtained, which would approximately represent the
relation between the efficiency of any one of these screws and its true
slip, if this curve were applicable to full sized screws propelling actual
ships. The slips in Fig. 5 being real or true, are not the slips of
commerce, which are the apparent slips, such as those given in the table.
Let us endeavor to split up these real slips into the apparent slips and
another item, the speed of the wake. We then at once meet with the
difficulty that the wake in which the screw works has not a uniform motion.
Complex, however, as are the motions of the wake, the screw may be assumed
to work in a cylinder of water having such a uniform forward velocity as
will produce the same effect as the actual wake on the thrust of the screw.
It is then readily seen that the real slip is the sum of the apparent slip
and the speed of the hypothetical wake. To make this clear, let V be the
speed of the ship, Vs the speed of the screw, _i.e._, revolutions × pitch,
and V the speed of the wake; then--

Apparent slip = Vs - V.
    Real slip = Vs - speed of ship with respect to the wake.
            " = Vs - (V - V) = (Vs - V) + Vw.
            " = Apparent slip + speed of the wake.

If the apparent slip be zero, the real slip is the speed of the wake, and
if the apparent slip be negative, the real slip is less than the speed of
the wake. The real slip is greater than the apparent slip, and can never be
a negative quantity. From Mr. Froude's model experiments, it appears that
this speed of wake for the A class of ship amounts to about 10 per cent. of
the speed of the A screw. If this value is correct, then the real slip is
(10 + 17.6) per cent., or 27.6 per cent. This is shown in Fig. 6, where O
is the point of no slip, being 17.64 from the point of real slip. Slips to
the right of O are positive apparent slips, slips to the left are negative
apparent slips. The vessel F would certainly have a wake with a speed
considerably less than that of A's wake. From the model experiments, the
wake for F is about one-half that for the A class, or, roughly, 5 per cent.
of the speed of the screw. For the ship F, O is the point of no apparent
slip, and the real slip is (5 + 11.4) or 16.4 per cent. For E, the point of
real slip is approximately the same as for F. For B and D, the positions on
the curve would be about the same. The ship B has a higher speed of wake
than D, but the screw D has the greater apparent slip. The influence of the
number of blades on the scale for the slip has been neglected. If this
efficiency curve were applicable to full sized screws propelling actual
ships, and if the determination of the wakes were beyond question, then we
should have a proof that our screws were at or near the maximum efficiency.
But, as we know, from the total propulsive efficiencies, that the screws
have high and not widely different efficiencies on these ships, we may
argue the other way, and say that there is good reason to consider that at
least the upper part of the curve agrees with experience obtained from
actual ships. Now take Fig. 6 and consider the general laws there
represented. Take the speed of the wake as 10 per cent. of the speed of the
screw, which is probably an average of widely different conditions,
including many single as well as twin screw ships. Then this curve shows
that considerable negative slips mean inefficient screws; that screws may
have very different positive slips without any appreciable difference in
their efficiencies; and that very large positive slips and inefficient
screws may be companions. For instance, a screw with a large positive slip
in smooth water is frequently inefficient at sea against a head wind, which
increases the resistance, and necessitates an increase of slip. I venture
to say that these statements, taken in a general manner, are not at
variance with experience obtained from the performances of screw ships.
Before it is possible to satisfactorily decide if this curve applies in a
general manner to full sized screws propelling ships, we require the
results of trials of various ships where the screws are working about the
region of no slip. Model experiments teach that the scale for the slip
varies with the design of the screw, and that with a given screw the speed
of the wake (which decides the point of no apparent slip) varies with the
type of ship and with the position of the screw with respect to the hull.
Remembering these disturbances, it is not improbable that it may be
possible to account for or explain what at first sight may appear
departures from the curve. The diameters of the screws in the table are not
compared with the diameters given by the method explained by Mr. Froude in
his paper last year, for there are differences in the slips, the
proportions of blade area to disk, and, to some extent, in the shapes of
the blades, which are not taken into account in that method. Assuming,
however, as Mr. Froude does, a constant proportion of blade area to disk,
and a uniform pattern of blade, the determination of the diameter for a
given set of conditions may, as a rule, be a complete solution of the
problem of the design of a screw, but these assumptions do not cover all
the necessities of actual practice, which make it extremely desirable to
know something about the influence or efficiency of various proportions of
blade area to disk, and of the form or distribution of a given area.

During the discussion which followed, Mr. John said that, both as regarded
the mercantile marine and the Royal Navy, there were few data to work upon,
but few ships having been built with twin screws. Mr. Linnington's
proportions of pitch to diameter of 1.2 to 1.34 was not invariably adhered
to. He mentioned a couple of small twin screw vessels where the proportion
of pitch to diameter came nearly to 1.5, and he remembered a few years ago
the propellers in one of these vessels being changed and the pitch
increased, the result being a very considerable improvement. He believed
they might go with quick running twin screw engines to a larger proportion
of pitch to diameter than they could with a single screw. He might instance
the change in the Iris. She was first engined with the pitch equal to the
diameter, and she gained two knots or thereabout when the diameter was
reduced 2 ft. and the pitch increased 2 ft.

Admiral De Horsey said that he tried experiments with the single screw in
the Aurora. She had a feathering serew, and when the sails were used to
assist, they commonly altered the pitch of the screw according to the
strength of the wind. The screw could be altered while it was revolving,
and as the wind freshened they coarsened the pitch, and when they wanted to
stop the engines they coarsened the pitch so as to bring the screw right
fore and aft, so that they never altered the way of the ship in changing
from steam to sail alone. The reason why twin screws had been adopted in
the navy was that if one was damaged there was the other still available.
But it gave them a still further advantage, as it enabled them to have a
fore and aft bulkhead, which with a single screw was difficult. The
mercantile marine had not as yet looked favorably on twin screws. Their
finest and fastest ships were single screws, probably because, in very bad
weather, the single screw was better.

Mr. Spyer said that in designing propellers for ships of war, they were
obliged to attempt to obtain the highest possible speed, and that was not
necessarily coincident with a propeller of maximum efficiency. On the other
hand, for mercantile purposes, coal consumption was obviously of paramount
importance, and the speed of any particular vessel must be obtained with
the smallest possible amount of indicated horse power, and a propeller of
maximum efficiency. Regarding the position of the propellers in a small
pinnace, the propellers were shifted six or seven inches further out, and
with about ten per cent. less indicated horse power she obtained three
tenths of a knot more speed.

Mr. Barnaby asked Mr. Linnington whether, in designing twin screws for a
vessel of 8,000 i.h.p., he would make each screw, which would have to take
4,000 i.h.p., of the same diameter as a screw for a single ship of 4,000
i.h.p., of the same speed. Unfortunately in high speed vessels, from one
point of view, the faster they went for a given power the smaller the
diameter of the screw had to be, and the larger the pitch, so that in very
high speed twin screw vessels the ratio of pitch to diameter would be found
to come out very great indeed. In a twin screw torpedo boat, to be tried
shortly, they had a ratio as high as 1.64. In the case of the Inflexible it
was found, owing possibly to the position of the screw, that the whole of
the plates immediately over the screws were damaged. Mr. Beckett Hill had
been using, during the past three or four years, the twin screw steamers
the Ludgate Hill, Richmond Hill, and Tower Hill. These were all over 4,000
tons register, and indicated, when at work at full speed, 2,500 h.p. Before
he and his friends built these steamers, they built some very large tug
boats on the twin screw principle. At the present moment, four of the
fastest steamers building for the Atlantic service were to have twin
screws. The great obstacle to the extension of the twin screw in the
mercantile navy had been the fear that the projection of these screws would
make the vessels very difficult to handle, but he had found no such
difficulties. He had found it an advantage to put the point of the
propeller as near the deadwood as he could, without actually touching it,
and in the large steamers, as well as in the tugs, the distance was a few
inches. As to the point of safety, he thought it a great advantage to have
twin screws, and on two occasions twin screw vessels had met with accidents
which, but for the twin screws, would have necessitated their putting back
to New York for repairs. The Richmond Hill, on one occasion, met with an
accident to her machinery two days after leaving New York; but she was able
to come on with the second set of engines, and was only one day late in the
passage. No difficulty had been found in the docking and undocking of these
vessels, either in London or Liverpool, and while with single screw vessels
they had sometimes to employ one or two dock boats to dock and undock them,
they never had to do so with the twin screw vessels. These vessels were 400
ft. long, with 48 ft. breadth of beam--a very large size to handle in a
river like the Thames. He noticed in the paper a propeller with a diameter
of 15 ft. 6 in. to indicate 11,110 h.p., so that a great Atlantic steamer,
which should indicate 11,000 or 12,000 h.p., and have a beam of about
65ft., would have her screws very well protected.

Mr. White said that as soon as it was found that with twin screws they lost
nothing in efficiency, ship owners generally were contemplating their
adoption, an admirable example of which had been set in the vessels of the
Hill line. In adopting twin screws, the question whether they should
overlap was one that deserved very serious consideration, and it was
interesting to know, from experience gained by the vessels of the Hill
line, that there was no difficulty in the way of the projection of the
screws. With a moderate power, and with vessels of considerable size, the
screws were well sheltered: but in the large ships which were contemplated,
where there must necessarily be larger screws, this might be different, and
become a difficulty.

Mr. Linnington, in reply, said there was no reason to think that the twin
screw at sea might not be as satisfactory, in comparison with the single
screw, as it appeared in smooth water. As a matter of fact, one of the
great advantages of twin screws was that at sea the condition of weather
which would bring the single screw out of the water, and make it extremely
inefficient, would have no appreciable effect on the twin screws. In
vessels of deep draught especially, they were well immersed, and they were
really more efficient at sea than in smooth water. In ships of full form,
the longitudinal position of the screws was of importance; but in the ships
referred to in this table the run was very fine, and the screws were well
covered by the hull. He did not think, in such a case, any small difference
in longitudinal position would affect the performance. If any alteration
were made, it would probably be better to put the screws farther off. When
the rudder was hard over, the blades of the screw should be about a foot
clear of the rudder.--_Industries_.

       *       *       *       *       *




RECENT ADVANCES IN SEWING MACHINERY.

[Footnote: A recent lecture before the Society of Arts, London.]

By JOHN W. URQUHART.


The distinct improvements in sewing machinery to which I would invite your
attention this evening have reference more particularly to the results of
inventive effort within the past ten years. But although marked development
in the machines has occurred in so short a time, it may be taken for
granted that those advances are but the accumulated results of many years'
prior invention and experience of stitching appliances.

The history of the sewing machine, and the decision of the great question,
Who invented an apparatus that would unite fabrics by stitches? do not at
present concern us. Many sources of information are open to those who would
decide that extremely involved problem. But whether the production of the
first device of this kind be claimed for England or for America, it is
quite certain that no one man invented the perfect machine, and that those
fine specimens of sewing apparatus shown here to-night embody the labors of
many earnest workers, both in Europe and America.

Most of us are familiar with the arrangements of an ordinary lock stitch
machine, and an able paper by Mr. Edwin P. Alexander, embracing not only a
good account of its history, but most of the elements of the earlier
machines, has already (April 5, 1863), been read before you. This, and
sundry descriptions of such apparatus in the engineering papers, confine my
remarks to the more recent improvements in three great classes of machines.
These are, briefly, plain sewing machines; sewing machines as used in
factories, where they are moved by steam power; and special sewing
machines, embracing many interesting forms, only recently introduced. We
have thus to consider, in the first place, the general efficiency of the
machine as a plain stitcher. Secondly, its adaptability to high rates of
speed, and the provision that has been made to withstand such velocities
for a reasonable time. And, thirdly, the apparatus and means employed to
effect the controlling of the motive power when applied to the machines.

To deal with the subject in this way must, I fear, involve a good deal of
technical description; and I hope to be pardoned if in attempting to
elucidate the more important devices, use must be made of words but seldom
heard outside of a machinists' workshop.

It appears scarcely necessary to premise that the sewing machine of twenty
years ago has almost faded away, save, perhaps, in general exterior
appearance; that the bell crank arms, the heart cams, the weaver's
shuttles, the spring "take ups," rectangular needle bars, and gear wheels,
have developed into very different devices for performing the various
functions of those several parts.

The shuttle is perhaps the most important part of a lock stitch machine.
But what is a shuttle? So many devices for performing the functions of the
early weaver's shuttle have been introduced of late, that the word shuttle,
if it be used at all, must not be accepted as meaning "to shoot." We have
vibrating shuttles, which are, strictly speaking, the only surviving
representatives of the weaver's shuttle in these new orders of machines;
and stationary shuttles, oscillating shuttles, and revolving shuttles,
besides the earlier rotating hook, in several new forms, difficult to name.
But the general acceptation of the word shuttle, as indicating those
devices that pass bodily through the loop of upper thread, is, I venture to
think, sufficiently correct.

Many changes have been effected in the form, size, and movements of the
shuttle, and we may profitably inquire into the causes that have induced
manufacturers to abandon the earlier forms. The long, weaver's kind of
shuttle, originally used by Howe and Singer, had many drawbacks. Mr. A.B.
Wilson's ingenious device, the lock stitch rotating hook, was not free from
corresponding faults. The removal of these in both has led to the adoption
of an entirely new class of both shuttles and revolving hooks. It is well
known that the lock stitch is formed by the crossing of two threads, one of
which lies over, and the other under, the cloth to be sewn. This crossing
point, to insure integrity of the stitch, must occur as nearly as possible
in the middle of the thickness of the fabric. The crossing must also be
effected while a certain strain, called tension, is imposed upon both
threads. If the tension of one thread should outweigh that of the other,
the locking point becomes displaced. If the tension be insignificant, the
stitches will be loose. If the tension should vary, as in the long shuttle,
there will occur faulty points in the seam.

In the earlier rotating hook the tension depended upon the friction
developed between the spool and the hook. This tension, therefore, varied
in proportion to the speed of the latter, and could never be constant. This
was quite apart from the frictional resistance offered to the upper thread
in passing over the cavity of the hook.

In the shuttle the tension was obtained by threading through holes in the
shell, or beneath a tension plate, as in Howe's machine. This tension, so
long as the reel ran between spring centers, was never constant. The
variation was chiefly due to the angular strain set up when unwinding from
the reel. This strain varied according to the point of unwinding. It was
light in the middle of the reel and heavy at either extremity. These
drawbacks caused immense anxiety to the first makers of sewing machines,
and numerous attempts to overcome them led to little improvement. With
reference to high rates of speed, the older shuttle, requiring a long and
noisy reciprocation, had its disadvantages.

The only effective remedy for these drawbacks was a radical one. It was
necessary to substitute depth of reel for length. Hence, several attempts
have been made to construct disk or ring shuttles. Many forms of those have
been tried. They all depend upon the principle of coiling up the thread in
a vertical plane, rather than in horizontal spirals. Some makers placed the
disk in a horizontal plane, and caused it to revolve. Nothing could be
worse, as will be seen, if we follow the course the enveloping loop must
take in encircling such a shuttle. But a complete solution of the
difficulty of employing a ring shuttle has been achieved in the oscillating
form, invented by Mr. Phil. Diehl, and known as Singer's (Fig. 1). A short
examination of it may profitably engage your attention. The shuttle itself
is sufficiently well known, but certain features of it, and to which it
owes its efficiency, appear to call for some explanation. Its introduction
dates back some years, during which time it has undergone certain
modifications.

[Illustration: FIG. 1.]

It consists of a thick disk bobbin of thread, _h_, fitting loosely in a
case constructed in the form of a bivalve, _a_ and _d_. This case is
furnished with a long beak, usually forming a continuation of the
periphery. The beak is intended to enter and detain the loops of upper
thread, and lead them so that they ultimately envelop the shuttle, a motion
of the thread which is chiefly due to the oscillation of the shuttle in a
vertical plane. The oscillating movement is to the extent of 180 degs. of
the circle, which suffices to cast the loops freely over the shuttle. The
center of oscillation is not coincident with the center of the shuttle; but
it is nearly so with the periphery of the thread reel, and exactly
coincides with the point where the under thread is drawn from the shuttle,
_g_. The shuttle thread is thus entirely freed from any tendency to twist,
an objection frequently urged against circular or revolving shuttles. It
will be observed, also, that the body of the shuttle is extremely narrow.
Bulging of the thread loops to one side or the other is thus obviated.

But the long beak in this description of shuttle serves an important
purpose other than that of seizing the upper thread loops, otherwise a very
short beak would be preferable. It adds so much to the efficiency of the
machine that a little further explanation of it appears essential. In the
old fashioned machines the thread required to envelop the shuttle was
dragged downward through the cloth, while the needle still remained in the
fabric. This necessitated the use of large needles with deep side channels,
to enable the thread to run freely, and as a consequence the punctures that
had to be made in the fabric were unnecessarily large, and could not in any
case be entirely filled by the thread, a condition which is now recognized
as essential in linen stitching and for waterproof boots.

The long beak in both shuttles and hooks offers an immediate solution of
the old difficulty experienced with long shuttles. When the needle begins
to rise, the shuttle commences to oscillate, through the loop, the motions
so coinciding that the long beak, c, merely detains the loop until the eye
of the needle has ascended above the cloth; then, and then only, does the
envelopment of the shuttle commence, and the thread required for it flows
downward through the puncture. The envelopment is completed before the
needle has attained its highest point, and the consequent loose thread is
immediately pulled up by a lever, called a positive take-up, before the
needle begins to descend for a fresh stitch. In this way little or no
movement of the thread is required in the cloth while the puncture made is
occupied by the needle. The result is the capability of such apparatus to
work with an incredibly fine needle--indeed, so fine as to be no thicker
than the incompressed thread itself. This would have been considered quite
impossible of accomplishment by our earlier machine makers. The advantage
thereby gained in stitching linen goods, and in sewing leather, where every
puncture of the needle should be quite filled by the thread, is at once
apparent. Indeed, a rubber or leather sack, stitched in this way, will
contain water without leakage--a very extreme test.

_Revolving Shuttles_.--The class of shuttles known as revolving or
rotating, and which really consist of a combination of the disk shuttle and
the earlier rotating hook of Wilson, have been under trial by several
makers for many years. If, for example, the oscillating shuttle we have
just examined were to complete its circular movement, it would constitute a
revolving shuttle, but would not be quite similar to those devices now
known as such. The most remarkable device of this kind yet introduced is to
be found in Wheeler & Wilson's machine known as No. 10 D, and invented by
Mr. Dials last year. It consists, in fact, of a detached hook, and its
inventor declines to class it with shuttles at all, styling it a detached
hook. It consists of an exterior shell or skeleton of steel, capable of
rotation in an annular raceway. Its detachment from the axis forms a
striking exception to the general construction of interlocking apparatus in
this company's machines. Under the beak of this curious device is found an
oblong recess, into which fits loosely a carrier or driver, rotating with a
differential or variable motion. The space between the carrier and the
sides of the recess is sufficient to permit the free passage of the thread
in encircling the shuttle, and the differential movement ingeniously
releases the contact between the hook and carrier. The skeleton of this
device is only one-sided, and does not really carry its bobbin in the
course of its revolution. The bobbin is placed in a cup-like holder, which
lies within the shuttle or hook body, and is retained in position by a
latch hinged to the bed of the machine. The cup and bobbin are prevented
from partaking of the rotatory movement by a steel spur projecting from the
cup, and fitting loosely into a notch in the latch. Tension upon the under
thread is obtained by passing it under a tension plate upon the bobbin cup.
Twisting of the thread is by these means entirely obviated. In this
apparatus, the disk-like appearance of the bobbin is partially lost in its
considerable breadth, and there is thus a distinct departure from the lines
of the ring shuttles before mentioned. The diagrams exhibit the hook in
several positions during its revolution, and the position of the threads
corresponding thereto.

[Illustration: FIG. 2]

_Fixed Rotating Hooks_.--Wilson's rotating hook for lock stitch machines,
and Gribbs' hook for single thread machines, are both well known. In the
year 1872, the Wheeler & Wilson company introduced a new hook, forming an
improvement upon Wilson's original device (Fig. 3). Its chief peculiarity
consists in the extension of the termination of the periphery, forming a
long tail piece, quite overlapping the point, and serving as a guard, both
to keep off the bobbin thread and to prevent collision between bobbin and
needle.

[Illustration: FIG. 3.]

This improved class of hooks are provided with a much deeper cavity than
those first introduced, an arrangement permitting of the employment of a
more commodious bobbin, which is generally covered by a cap, as in the
revolving shuttle, but free to revolve. In some cases the cap carries a
tension plate preventing its revolution with the hook. But beyond these
improvements on Wilson's original device, the utility of the hook mainly
depends upon two things quite apart from the hook itself. These are the
dispensing with the old fashioned check brush and the use of a positive
take-up.

Thus, in the original machine, the stitch was pulled up by the succeeding
revolution of the hook. For while one revolution sufficed to cast it over
the spool, a second turn was requisite to complete the stitch. In this way,
to make a first stitch with such an apparatus required two turns of the
rotating hook. The improvements mentioned enable the machine to complete a
stitch with one turn of the hook--an important step in advance, when we
consider that by the old method each length of slack thread must be
tightened up solely through the fabric and the needle eye. But this
particular arrangement bears so much upon the introduction of the positive
take-up itself that further reference to it must be reserved until that
device has been described.

_Simple Thread Hooks_.--The best known of these is Willcox & Gibbs. It has
been so often described, that no further reference to it may be made. It
continues to make the same excellent twisted stitch as it produced
twenty-five years ago.

_Of Vibrating Shuttles_.--These are shuttles of the long description,
moving in a segment of a circle. There are several varieties. The most
novel machine of this kind is the vibrating shuttle machine just produced
by the Singer Manufacturing Company. In this case the shuttle itself
consists of a steel tube, into the open end of which the wound reel is
dropped, and is free to revolve quite loosely. Variation of tension is thus
obviated in a very simple manner. The chief point of interest in the
machine is undoubtedly the means employed in transferring the motion from
the main shaft to the underneath parts, an arrangement as ingenious and
effective as any device ever introduced into stitching mechanism. It is the
invention of Mr. Robert Whitehall, and consists of a vertical rocking shaft
situated in the arm of the machine Motion is imparted to it by means of an
elbow formed upon the main shaft acting upon two arms, called wipers,
projecting from the rocking shaft, the angle formed by the arms exactly
coinciding with that of the elbow in its revolution. This admirable motion
will no doubt attract much attention from mechanists and engineers.

_The Lock Stitch from Two Reels_.--In the early days of the sewing machine,
the makers of it often met with the question, "Why do you use a shuttle at
all? Can you not invent a method of working from a reel direct?" The
questioner generally means a reel placed upon a pin, just as the upper reel
is placed. The reply to such a query is, of course, that to produce the
lock stitch in that way is impossible--as indeed it is.

But many ingenious machinists have pondered long over the problem, and
several clever contrivances have been invented with a view to its solution.
It may scarcely be necessary to say that the best manufacturers of sewing
machines have conducted experiments with the same object in view, and the
result has always been a return to the shuttle, with its steel bobbins.

Why is this, and how is it that a very big shuttle cannot be used, large
enough, indeed, to accommodate any bobbin within itself? The answer is very
simple. It has been done over and over again.

Since the whole bulk of the under thread must pass through the loop of the
upper one, it, is quite clear that the size of that loop must be
proportioned to the bulk of the shuttle. Thus, a small shuttle would,
perhaps, be covered by an inch of thread, while our supposed mammoth
shuttle might require ten times that amount. Now, let us consider that to
sew an inch of thread into lock stitches frequently involves its being
drawn up and down through both needle and fabric twenty times. This means
considerable chafing, and possible injury to the thread.

But if we were to sanction the use of capacious shuttles, ten inches of
thread must undergo this chafing and seesaw treatment, and under the above
conditions every part of the ten inches must pass up and down two hundred
times--treatment that might reasonably be expected to leave little "life"
in the thread. But in spite of this tremendous drawback, there are machines
offered for sale made with such shuttles.

For reasons that I have now pointed out, it is quite clear that a large
shuttle or bobbin is by no means an unmixed advantage. Indeed, the very
best makers of sewing machines have always striven to keep down the bulk of
the shuttle, and in those splendid machines shown here to-night the use of
the small shuttles is conspicuous. It may be contended that small bobbins
frequently require refilling, which is quite true, but the saving of the
thread effected thereby, not to mention that of the machine itself, amply
compensates for the use of small shuttles. Apart from this, however, it is
no longer necessary to wind bobbins at all. Dewhurst & Sons, of Skipton,
and Clark & Co., of Paisley, have produced ready wound "cops" or bobbins of
thread for placing direct into shuttles. Thus no winding of bobbins is
necessary, and indeed the bobbins themselves are dispensed with. I believe
that the slightly increased cost of the thread thus wound is the only
present bar to the extensive introduction of ready wound "cops."

_Of Thread Controllers_.--One of the earliest difficulties encountered by
the maker of a sewing machine was that of effectually controlling the loose
thread after it had been cast off the shuttle. In some machines this slack
thread amounts to six, in others to one or two inches. Howe got over the
difficulty by passing his thread, on its way to the needle, over the upper
extremity of the needle bar--the ascent of the bar, then, sufficed to pull
up the slack. Singer improved upon this by furnishing his machine with a
spring take-up lever, partially controlled by the needle bar.

[Illustration: FIG. 4.]

Wilson, in the Wheeler-Wilson machine, had neither of those arrangements,
but depended upon the succeeding revolution of the hook to draw up the
slack of the preceding stitch. These devices were all far from perfect in
their operation, chiefly because they commenced to act too soon. In each
case the pulling up commenced with the rise of the needle, and the
tightening operation subjected the thread to all the friction of rubbing
its way through both needle eye and fabric. Now, an ideal take-up should
not commence to act until the needle has ascended above the fabric, and one
of the most important steps toward perfection in sewing machines was
undoubtedly attained when such a device was actually invented. In effecting
this, the means employed consists of a differential or variable cam,
rotating with the main shaft. This controls the movements of a lever called
the take-up, pivoted to the machine (Fig. 4). Not only has it been
possible by these means to control the tightening of the stitch, but the
paying out of the thread for enveloping the shuttle also, and both the
paying out and pulling up are actually effected after the needle has
ascended above the cloth. The introduction of the positive take-up, the
first forms of which appeared in 1872, not only simplifies the movements of
the shuttle or hook, but for the first time renders the making of the lock
stitch possible, while the needle has a direct up and down motion. Thus, we
find that in most of the swiftest sewing machines, the needle bar is
actuated by a simple crank pin or eccentric, there being no loop dip or
pause in its motion.

The diagram shows a positive take-up in three positions--at the
commencement of the needle's descent, during the detention of the loop by
the beak, and during the casting off of the loop. The dotted lines indicate
the path of the cam to produce these positions. The intermittent movements
of the take-up have thus led to the abandonment of variable motions in both
needle and shuttle, and particularly so in oscillating shuttle machines.

_Wheeler & Wilson's Variable Motion_.--But while the simple and direct
movement is now preferred for shuttles, both oscillating and rotary, the
revolving hooks of Wheeler & Wilson are provided with a differential
motion, and the way it is effected appears sufficiently interesting to call
for a short description. When the rotating hook has seized the loop of
thread, it makes half a revolution with great rapidity; its speed then
slackens, and becomes very slow for the remaining half a revolution. In the
first machines introduced, this was effected by means of a revolving disk,
having slots in which worked pins attached to the main shaft and hook shaft
respectively.

[Illustration: FIG. 5.]

In the later and more improved machines, the variable device is much
simplified (Fig. 5). The main shaft, leading to the rotating hook, is
separated into two portions, the axis of one portion being placed above
that of the other. A crank pin is attached to each, and these pins are
connected together by a simple link. An examination of the device itself
shows that, while the motion of the main shaft portion is uniform, that of
the hook shaft is alternately accelerated and retarded.

The picture on the screen gives a general view of the No. 10 D machine, in
which these motions are embodied, and showing the position of the positive
take-up affected by those motions, a position which is preferred for very
high speeds in this machine, especially for threads possessing little
elasticity.

_Motions of the Feeder_.--The speed attained by the fastest sewing machines
is due more to the reduction and simplification of the movements than to
any other improvement. Heavy concessions and reactions have been replaced
by direct motions, and cams have been excluded as much as possible. Mr.
A.B. Wilson's famous invention of the four motion feeder depended upon both
gravity and a reacting spring for two motions. Singer improved upon it by
making three of the motions positive, a spring being used for the drop. But
a really positive four motion feeder was long sought by inventors.

Hitherto the reaction of the feeder--that is, its descent and
recession--was generally attained by means of a spring. The drop and ascent
are now effected by means of a separate eccentric in Singer's machine.
Uncertainty of action in the feed, once a cause of much inconvenience, may
now be said to be overcome. A peculiarity of the four motion feeder in
Wheeler & Wilson's machine is an arrangement enabling the operator to feed
in either direction at will.

Not less worthy of note are improvements that have been made in wheel
feeders. The wheel feed was originally much used for cloth sewing machines,
especially in Singer's system. But in recent years the drop or four motion
feeder has entirely superseded it for such purposes. The wheel feed still
holds its own, however, for sewing leather, especially in the "closing" of
boot uppers, in this country. Singer's original wheel feeder was actuated
by a friction shoe riding upon the flange of the wheel. The friction grip,
however, had certain faults, owing to the tendency of the shoe to slip when
the surfaces became covered with oil.

[Illustration: FIG. 6.]

A later form of Howe's machine used a pair of angular clutches, embracing
the flange of the wheel. In both Singer's and Wheeler & Wilson's latest
styles of machines this arrangement is simplified and improved by the use
of a single angle clutch, which is found to work even when the surfaces are
freely oiled (Fig. 6).

Any motion of the free extremity of the lever upon which the biting clutch
is formed binds the latter upon the flange of the wheel, which then
advances so long as the lever continues to move in that direction. When the
stitch is completed, the clutch is allowed to recede, and is pulled back by
a reacting spring. The bite of the clutch is given by the two opposite
corners.

The feed wheel itself is free to revolve in a forward direction, but is
prevented from rocking backward in Singer's machine by an ingenious little
device, recently introduced. It consists of a small steel roller, situated
within the angle formed by an inclined plane and the flange of the wheel,
and constantly pulled into the angle by a spiral spring. Any backward
tendency of the wheel binds the roller more firmly in the angle and stops
the wheel. Former feed wheels were checked by a brake spring or block,
which retarded the motion of the whole machine when heavily adjusted.

_Feeders for Button Hole Sewing Machines_ are almost invariably of the
wheel type, but in this case the cloth is usually carried by a clamping
device, and moved in a pear-shaped path by means of a cam cut in the feed
wheel, as shown in the samples of this wonderful kind of mechanism
exhibited here to-night.

_The Compensating System of Construction_.--Compensation for wear is a part
of the mechanist's art that appears just as essential to him as
compensation for variation of temperature is to a maker of chronometers. In
the construction of sewing machines to be run in factories by power at
their utmost speed, such a system is of the greatest importance. An
effective _system_ of compensation has been eagerly sought by the best
machine makers ever since the introduction of fast speed sewing.

Compensation has been attempted here and there in the machines for many
years, but no sewing apparatus could be said to be so compensated until the
cone compensator came into use, a device which has been taken advantage of
by various makers. Save in the shuttle race itself there is not a part of
the oscillating shuttle machine subject to serious wear that cannot be
instantly adjusted to full motion by the turning of a screw, while wear in
the shuttle race can be compensated for in the usual way. This effective
system depends upon the union of two mathematical forms, long used in
mechanism--the _cone_ and the _screw_. In screw cones we possess a perfect
compensator, and it is surprising that parts of mechanism so hung appear
subject to very little wear. Another advantage, too, is gained by the
introduction of screw cone bearings; the friction is always greatly reduced
by their use. In every case the fine adjustment of the cones is securely
maintained by locknuts (Fig. 7).

[Illustration: FIG. 7.]

But the screw cone system is not the only compensator used in sewing
machinery; where it cannot be easily introduced, other devices have been
employed.

The well known tapering needle bars of former years have been superseded by
cylindrical needle bars. The Wheeler & Wilson Company appear to be the
first who utilized the engineer's shifting box as an antifriction device
for round needle bars. They packed their bars round with felt rings, and
compressed the whole by a screw cap.

In the Singer machines the same excellent device has been adopted, hemp
packing and screw bushes being used (Fig. 8); _f_ and _g_ show the direct
action on the needle bar. This method of forming needle bar bearings,
partially of metal and partially of felt or hemp, has afforded the most
surprising results.

[Illustration: FIG. 8.]

When the bars are of hard or finely polished steel, no perceptible wear can
be detected in them, even after they have been in daily use in factories
for twelve months, whereas bars not so bushed might show considerable wear
in that space of time. The packing, to be effective, should be sufficiently
close to prevent as much as possible friction of the steel with the cast
iron needle bar ways. Lubrication of the steel is insured by keeping the
hemp packing moistened with oil.

Cylindrical needle bars, when combined with an effective system of
brushing, have proved themselves superior to every other form of slide for
lock stitch machines. But their introduction is by no means a thing of
yesterday. They were used freely in sewing machines as far back as 1860,
but were never very successful until united with the lubricating brush.
Some makers go a step further, and elaborate the system by the introduction
of steel brushes, easily renewable.

Every effort is now made to reduce, as much as possible, not only the
extent of movement of the parts in high speed machines, but the weight of
the parts themselves. Indeed, so far has this been carried that, in some of
the Wheeler & Wilson machines now shown, the needle bars consist really of
steel tubes. Small moving parts are made as light as possible, but rigidity
is secured by the free use of strengthening ribs. Many of the parts are of
cast iron, rendered malleable by annealing, and finally casehardened. Such
parts are found to be quite as durable as if made of forged steel, and are,
of course, less costly. As to the automatic tools now used in the
construction of the machines, it may be said that scarcely a file, hammer,
or chisel touches the frame or parts while they are being assembled to work
together. The interchangeable system of construction is, of course, the
only one possible for the accurate production of the millions of sewing
machines now manufactured annually.

_High Arm Construction_.--Sewing machines, as now constructed, exhibit a
rather short and very high arm, a form of framework that has been found to
contribute in no small degree to the light running capabilities of fast
speed machines. While it reduces the length of the various parts concerned
in the transference of the motive power, it adds to their rigidity and
diminishes their weight, maintaining at the same time the capacity of the
machine to accommodate the largest garments beneath the arm.

But the specific improvements in plain sewing machines, to which I have had
the honor of drawing your attention, do not exhaust the list, and, time
permitting, it might be considerably augmented. Nor must it be inferred
that advancement has taken place exclusively in those systems of sewing
machinery now before us.

_Accessories to Sewing Machines_.--The number of special attachments that
have been successfully adapted to plain sewing machines has multiplied so
rapidly of late, that only one or two of the more notable can be spoken of
on this occasion. Perhaps the most generally useful of these is the
trimmer, an arrangement consisting of a vibrating knife, which trims off
the superfluous edge of a seam as the machine stitches it. These are in
extensive use in the factories at Leicester, Nottingham, and elsewhere,
while Northampton and Norwich use the same device for paring the seams in
boot upper manufacture. The chisel-like knife is usually actuated by a cam
rotating with the main shaft, and one or two of the usual forms of this
attachment are to be seen here this evening on both lock and loop stitch
machines.

When machines are moved by the foot, there are many objections to running
the whole machine while winding the shuttle reels. We have, therefore,
several useful devices for releasing the balance wheel of the machine from
the main shaft, while winding. These are to be found both on Wheeler &
Wilson's manufacturing machine and upon Singer's highly finished "Family"
machine, which also carries a most ingenious automatic reel winder, capable
of doing all the work itself, and ceasing to act as soon as the bobbin is
filled.

The setting of the needle in a sewing machine was once quite a task.
Ofttimes it had to be adjusted by chance, in other instances by certain
guiding marks upon the needle bar. It is gratifying to know that all this
has been done away with, and that the needle has only to be inserted into
the bar, and fastened by turning a small screw. These are styled
self-setting needles, and are usually so arranged that they cannot be
adjusted wrongly as to the position of the eye.

In the Willcox & Gibbs machine, and in Singer's single thread machine,
shown here, we have an intermittent tension arrangement, which clamps the
thread at the right moment, and differs from ordinary tension devices,
inasmuch as it may be said to be automatic. The feeder, too, on these
machines is of excellent design, while the arrangements that have been
introduced into the Willcox & Gibbs straw hat sewing machine are
surprisingly effective in spinning up a hat from a loose roll of braid.
Speaking of straw hat machines, mention should be made of Wiseman's hand
stitch apparatus, as improved by Messrs. Willcox & Gibbs, and shown here
this evening. This machine employs two needles, and makes a stitch
resembling hand work at intervals, producing a short stitch at the center
of the hat, and automatically widening the space between the stitches as
the distance from the center increases. The machine itself is of wonderful
ingenuity, and must be examined to be understood.

The stitch making itself is, I believe, quite new, and is also of much
interest. A pair of needles, the width of a stitch apart, rise from beneath
through the material. One of these is an ordinary machine needle, threaded;
the other is a barbed needle. After rising above the surface, the loop of
the threaded needle is seized by a "threader," and thrown into the barb of
the barbed needle. The needles then descend, and the feed occurs, being the
length between stitches. Upon the ascent of the needles again against the
material, the loop is both given off the barb and is entered by the
threaded needle, completing the stitch.

_Of Button Hole Machines_.--The mechanism of button hole machines is so
intricate, that I can only attempt on this occasion to partially elucidate
the construction of one of them, recently introduced, namely, Singer's,
which automatically cuts, guides, and stitches the work.

[Illustration: FIG. 9.]

Fig. 9 exhibits the stitching made by this machine upon the edge of the
button hole. Fig. 10 represents the right and left hand loopers and loop
spreaders, and for the stitch making. They rock from right to left with an
intermittent motion obtained from a cam. The left hand looper carries the
under thread and interweaves it with the upper, forming the stitch,
originally invented, I believe, by Mr. George Fisher, of Nottingham, and
reinvented for the button holing machine by D.W.G. Humphreys, of
Massachusetts, U.S.A., in 1862. The loop spreaders are moved by a roller
carried upon the looper frame. Fig. 11 exhibits the feeding arrangement,
both sides of the feed wheel, the driving lever, and the shape of the path
given to the carrying clamp by the heart cam cut in the upper surface of
the feed wheel. The picture on the screen represents the upper portions of
the machine, exhibiting the conveying clamp, the to and fro dipping motions
of the needle bar, and the parts conveying motion to the arrangements
beneath the bed plate. These are shown in Fig. 12, and represent the feed
and looper cams, the feeding and looper levers, and the stitch forming
mechanism already shown. A most ingenious device in this machine is the
arrangement for automatically lengthening the throw of the feed while
stitching around the eye of the button hole. It is effected by means of a
cam, which imparts more or less leverage to the feed arm by the
intervention of a "shipper" lever, hinged to the feed lever itself. The
space of time at my disposal obliges me to recommend a personal examination
of the machine itself, to fully understand its various motions and its
action in working a button hole.

[Illustration: FIG. 10.]

[Illustration: FIG. 11.]

[Illustration: FIG. 12.]

Mention may be made of Singer's special button hole machine for making the
straight holes used in linen work, and in which a shuttle is employed. Of
Wheeler & Wilson's ingenious button hole machine for the same purpose, I am
enabled to show a diagram, in which it will be observed that the feeding
arrangements are placed above the bed plate, and are no doubt thereby
rendered easily accessible.

_Application of Power to Sewing Machines_.--There was a time when a cry
arose to the effect that the introduction of mechanical sewing would lead
to divers calamities, physical and mental. The ladies were to become
crooked in the spine, and regular operators were to become regular
cripples. It is scarcely necessary to ask, Has this been so? The operators
of to-day are, I think, superior in physical attainments to their sisters
of the needle and thread fifty years ago.

Within the past few years a revolution has taken place in the moving of
sewing machines. Domestic machines will probably always be driven by foot
power, spring, electric, and water motors notwithstanding. But the age of
treadles in the great manufacturing trades is a thing of the past. It was
not necessary for Parliament to step in and protect the workers, as was
frequently suggested by alarmists. The commercial interests of
manufacturers themselves were at stake. Machines driven by power could do
25 per cent. more work than those moved by foot. The operators, relieved of
the treadling, maintained a much better working condition; and altogether
the introduction of power driving, once well tested, became a necessity.
Power sewing machinery was speedily devised and introduced by several of
the first manufacturers, controllers of the speed of the machines followed,
and two or three splendid systems of stitching by steam power were soon
widely known.

By the kindness of three of the best manufacturers of power sewing
machinery, I am enabled to show to you, this evening, the best known
systems, arranged just as they are fitted in many large factories, as also
a sketch of the arrangements of Wheeler & Wilson's system. We have in the
first place a light shafting carrying a band wheel opposite to each
machine. By the use of a powerful electromotor, the shafting is caused to
rotate at the rate of 400 revolutions per minute by electricity. The
current is generated by the Society's dynamo machine, and is conveyed here
by copper cable. I do not know of any instance of sewing machinery in a
factory being driven by an electromotor, but such means of conveying motive
power appears admirably adapted for that purpose, when the stitching room
happens to be far removed from the main shafting or engine. But with regard
to motors for sewing machines, when special power has to be fitted down for
that purpose, my own experience leads me to speak in favor of the admirably
governed "Otto" gas engines made by Crossley Bros. These are especially
steady, a feature of no small moment in moving stitching machinery of
various kinds.

Much attention has been devoted to the invention of controllers of the
motive power supplied to sewing machines. The principle of the friction
disk has found most favor. In many cases two of these plates, fast and
loose, are placed upon the main shaft, and their separation and contact
controlled by the treadle. The great sensitiveness of the friction
attachment employed by the Singer company is due chiefly to the
transference of the friction plates to the axis of the machine itself (Fig.
13). Their contact and separation are controlled by a lever worked by a
very slight movement of the treadle. But the chief point of interest in
this device lies in the combination with the lever of a brake, enabling the
operator, by a simple reversal of the treadle's motion, to instantly
suspend the rotation of the machine. The forked lever, in fact, acts
simultaneously in throwing off the motion and applying the brake. The speed
is always in direct proportion to the pressure exerted upon the treadle,
and a single stitch can be made at will. Fig. 14 shows the friction wheel
separated, the portion a being fast, and e loose.

[Illustration: FIG. 13.]

[Illustration: FIG. 14.]

The Wheeler & Wilson company do not confine themselves to any particular
controller, but prefer the form shown here this evening (Fig. 15), in which
two bands and an intermediate pulley are employed. The first band is left
rather loose, and the machine is set in motion by the tightening of this
band through the depression of the treadle. The speed varies in proportion
to the pressure applied, and the sensitiveness of the arrangement is
increased by a brake device coming into play by the reversal of the treadle
as before.

[Illustration: FIG. 15.]

Messrs. Willcox & Gibbs depend upon a similar device shown in three
varieties to-night.

_Speed of Power Sewing Machines_.--The fastest practicable speed of a
machine worked by the foot appears to be 1,000 stitches per minute. Most
operators can guide the work at a much higher rate, especially in tailoring
or on long seams. The average speed upon such work is 1,200 stitches per
minute; but many lock-stitch machines are run at 1,500 and 1,800 per
minute, and even at much higher rates. There is always a limit to be
imposed upon speed by the guiding powers of hand and eye; it is this limit,
and not the capability of the machine, that confines the rate of driving.
Willcox & Gibbs' single thread machines are run in many instances at 3,500
stitches per minute. We have before us a single thread Singer machine
(appropriately named the "Lightning Sewer") and a Willcox machine, moving
at the enormous rate of 4,500 stitches per minute, and producing good work.
But it is doubtful whether such very great velocities can ever be
advantageously employed. Upon collar work, and in sewing boot uppers, the
rate seldom rises above 1,200 with advantage. If the machines be speeded
too high in any trade, the operator never uses the excess, and it only
proves a drawback. I seen the heaviest and hardest kind of navy boots
stitched at 1,500 to the minute upon Singer's lock-stitch machines. Wheeler
& Wilson's No. 10 D machine has been run by them, I am informed, as high as
2,500 to the minute. Loop-stitch machines, when well made, can be actually
run as high as 6,000, but 4,500 is, I believe, the maximum yet used for
this class of machine, even experimentally. There can be no doubt that
lock-stitch machines can be run as high as 3,000. The actual speeds of the
lock-stitch machines shown here upon the power stand average 1,300; those
of the chain stitch machines vary from 1,200 for the sack sewing machine to
4,500 for the small or single chain stitchers. Any of the latest styles of
either lock stitch or single thread machines can be run far faster than any
known expert operator can possibly guide the work under it.

It is very improbable that such speeds will ever be exceeded. The limit has
no doubt been reached. Very high speed is generally a delusion, and either
results in indifferent work, or actually retards its progress. Some idea of
the speed of the single thread machines now shown may be gathered from the
fact that, running at 4,500, and making eight stitches to the inch, they
accomplish over fourteen yards of sewing every minute.

Of special machines of interest, and which are too unwieldy to be shown
here, I am enabled to exhibit a few photographs.

One of the most novel of these is the "Twin" machine, designed by the
Singer company for the connecting together of the Jacquard cards used in
lace machines. The operation was formerly performed by hand. It is now done
by machine at less cost. The cards are placed upon a feeding drum, and fed
beneath a pair of needles. The laces forming the connection between the
cards are fed above and beneath, in line with the needles, and the whole is
easily stitched together. An extension of the same device is the multiple
machine, in which four needles and shuttles are used, sewing all the four
seams at one operation. This method of linking the cards is considered
better than similar work done by hand.

Of Wheeler & Wilson's new factory, at Bridgeport, and of the Singer
company's great new factory near Glasgow, I am enabled to exhibit
photographic views.

Before drawing my remarks to a close, I would briefly indicate the nature
of the various machines shown upon the power benching. Of the Singer
system, there are four. A drop-feed oscillating shuttle machine for
manufacturing purposes; a wheel-feed oscillating shuttle machine, furnished
with a trimmer, used chiefly in stitching leather and boot uppers; double
chain-stitch machine, used for sack making, now shown for the first time;
and a single thread "Lightning Sewer," fitted with a trimmer for hosiery
work. Of Wheeler & Wilson's system, there is a drop-feed manufacturing
machine with the new detached hook and latest improvements; a No. 10
machine with the usual hook, a wheel feed and trimmer, and a smaller
machine of the same type with drop feed. Of Willcox & Gibbs' system, there
is the ordinary single-thread machine for manufacturing, a single-thread
machine, with a trimmer, as used in the hosiery trades, and a machine
specially used for straw hat making.

We have here a small Singer machine, riding upon the edge of two pieces of
carpet, a carpet machine weighing ten pounds. When the handle is turned, it
stitches and travels over the edges, uniting them faster and more securely
than six hand sewers; and several others, representative of the family type
of sewing machine, besides Wheeler & Wilson's hemstitch machine, the
working of which is of much interest.

I would now invite those of you who seek a better acquaintance with those
curious and novel machines to freely examine and test the various types to
be found upon the power benching and upon stands. One or two operators will
come forward and show some of the capabilities of the machines upon actual
work, in which the making of a straw hat will perhaps show what can be done
in a few minutes by quick speed and expert fingers; but these performances
must not be regarded in the light of competitive tests between the
manufacturers showing them, and are intended merely to show the utility of
motive power driving.

In conclusion, I desire to thank those gentlemen at the head of the leading
firms of sewing machine manufacturers for the trouble they have taken to
arrange for your inspection specimens of their excellent systems, and I
have much satisfaction in expressing my obligations to them for ready
assistance in the preparation of my paper.

       *       *       *       *       *

Power machines and treadle machines were exhibited by Messrs. Willcox &
Gibbs, Messrs. Wheeler & Wilson, and the Singer Manufacturing Company. The
motive power was provided by an electrical motor, supplied by Mr. Moritz
Immish. The Howe Machine Company exhibited a model of the first machine
made by Elias Howe, and also one of the most recent Howe machines. Mr.
Newton Wilson showed a model of the Saint sewing machines, constructed from
Thomas Saint's patent specification, 1790, and Mr. Carver showed the
Standard sewing machine.

       *       *       *       *       *




THE NEW KRUPP GUNS.


Nothing is being talked about at present in Germany but the guns of great
caliber that are manufacturing at the celebrated works on the banks of the
Ruhr. As our neighbors appear to be elated over this wonderful work, it is
expedient to examine the subject, in order to see whether their applause is
legitimate.

We have known for a long time that the artillery _materiel_ devoted to the
defense of the German coasts consists of a long, stationary 5¾ inch gun; of
long 7¾ inch hooped steel guns, closed by a cylindrico-prismatic wedge; of
an 8 inch mortar; and of guns of 11¾ and 15 inch caliber. The 11¾ inch gun
is 22 feet in length, and, including the closing mechanism, weighs 79,200
pounds. As regards the projectiles that this weapon throws, the _ordinary_
shell is 33 inches in length, and weighs, all charged, 656 pounds, and the
_exploding_ shell, of the same length, weighs, all charged, 1,160 pounds.
The initial velocity of the latter is 1,600 feet with a maximum charge of
148 pounds of powder.

The 15 inch gun is 32.8 feet in length, and weighs 158,400 pounds. Its
projectiles are 3.67 feet in length. The _ordinary_ shell, charge included,
weighs 1,400 pounds, and the exploding shell, under the same circumstances,
1,700 pounds, that is, more than three quarters of a metric ton. The
initial velocity of this last named projectile is 1,650 feet with a maximum
charge of 1,650 pounds of powder. We also know that Mr. Krupp has two
models of guns of 13½ inch caliber, and of a length equal to 35 times the
caliber, say 39-5/12 feet. The lighter of these models (which was shown at
Anvers) weighs no less than 264,000 pounds, carriage not included. Its
cylindrico prismatic closing mechanism (_Rundkeilverschluss_) alone weighs
82,500 pounds. This is the weight of a 5¾ inch hooped steel gun!

[Illustration: FIG. 1.--NEW 52 FOOT KRUPP GUN AND A GERMAN FIELD PIECE
FIGURED ON THE SAME SCALE.]

We now learn that the Essen works have just begun the manufacture of a
314,600 pound gun. This piece, called "40 cm. kanone L/40," will, of
course, be of 15.6 inch caliber, but it will differ from the one above
described in that its length will be equal to 40 times the caliber, say 52
feet, or to the space occupied on the maneuvering ground by a field piece
drawn by six horses (Fig. 1). This gun will be provided with two kinds of
projectiles. One of these, called _light_, will be 3½ feet in length, weigh
1,628 pounds, and be capable of taking an initial velocity of 2,410 feet
and of piercing, on its exit from the chamber, either a hammered iron plate
3¾ feet in thickness or two united plates 1¾ and 2¾ feet in thickness.

The shell called _heavy_ will be 5¾ feet in length, and weigh 2,310 pounds,
say more than a 4¾ inch siege piece! The charge employed will be 1,067
pounds of brown, prismatic Dunwald powder. Ten hundred and sixty-seven
pounds--nearly half a metric ton, more than the weight of a field piece
without its carriage! With this enormous charge, the heavy shell will be
capable of an initial velocity of 2,100 feet and of piercing, on its exit
from the chamber, either a hammered iron plate 4 feet in thickness or two
united plates 2 and 2.88 feet in thickness.

The _Cologne Gazette_, from which we borrow most of the data just
presented, adds that the "40 L/40" piece will be the largest cannon in the
world, but that it will not long enjoy the privilege of such pre-eminence.
It appears, in fact, that Mr. Krupp is preparing to manufacture a gun of
17½ inch caliber, weighing 330,000 pounds. The projectile for this monster
will be 6 feet in length, say the stature of a full grown man, and will
weigh no less than a ton and a half. A man of medium stature will measure a
little less than this projectile (Fig. 2).

It is possible that all these figures have been slightly exaggerated by the
ultra-Vosges journals, who doubtless intend to make an impression upon us;
but we shall not dwell upon that point.

As regards the penetrating power of the large "40 L/40" gun, the German
press observes that in 1868 artillery was incapable of piercing in
one-hundredths of an inch what it is now piercing in tenths of an inch. The
principle was formerly admitted, it says, that a shell should by right have
a thickness equal to its caliber. Now, "the largest cannon in the world"
perforates a plate whose thickness is three times the diameter of the gun's
bore. What great progress! exclaim the German journals, and how jealous the
French and English are going to be! Jealous of that? Why, indeed? We are
not the least in the world so. How could we be? In the first place, we have
a gun of very great caliber--a 13¼ inch steel coast and siege piece. This
weighs 37 tons, and is 36¾ feet in length. Its projectile weighs from 924
to 1,320 pounds, according to its internal organization. Its conoid head is
very elongated, and by reason of this elegant form it always falls upon its
point, even at falling angles of an amplitude approaching 60 degrees. The
charge used varies from 396 to 440 pounds, according to the nature of the
powder. As for the ballistic properties of the piece, they are very
remarkable. Its projectile has an initial velocity of 2,132 feet, and the
maximum range is from 10 to 11 miles, say the distance from Paris to
Montgeron by the Paris-Lyons-Mediterranean railroad, or from Paris to
Versailles. Finally, the accuracy of this gun is much greater than that of
the 9½ inch steel one. Now, the accuracy of this latter is such that it is
impossible for its projectiles to miss a ship under way, and that we are
sure of playing with it against the enemy that game whose device is "We win
at every shot!" Well, we do not hesitate to say that these results appear
to us to be satisfactory--we mean quite sufficient--and that there is no
need of looking for a better gun. If there were, French industry would be
capable of producing weapons of any caliber desired. As regards this, there
is, so to speak, no limit; moreover, taking into account merely the
terrestrial conditions of the problem, we may be satisfied that the great
works of our country are more powerfully equipped than those of Essen, and
consequently better able to forge large pieces of steel.

Mr. Krupp, it is said, is very proud of his two power hammers, which he has
named Max and Fritz. But, on the whole, these two apparatus are only fifty
ton ones, and have a fall of but ten feet. Now, Creusot and St. Chamond
each has a hundred ton steam hammer with a fall of 16 feet, accompanied
with four furnaces and four cranes.

[Illustration: FIG. 2.--3,300 POUND PROJECTILE OF A KRUPP GUN IN COURSE
OF MANUFACTURE.]

But why proceed to the manufacture of monstrous guns, like those that Mr.
Krupp has just produced, or meditates producing in the future; guns of such
a caliber can be used only in special cases--in battery on the coast or on
board of a ship. It is not with _materiel_ of this kind that war is waged;
it is with field pieces. Our ultra-Vosges neighbors well know this.

One of the reasons that the war that very recently threatened us did not
break out, was because the Germans could not fail to see that their field
_materiel_ was not as powerful as ours; that the shell of our 3½ inch gun
weighs 17½ pounds, while that of their heavy 3½ inch gun does not weigh 15.
Now, this difference has its value.

Hunters well know what importance it is necessary to attach to the number
of the ball that they use.

This granted, it is well to observe that the net cost of the "40 cm. kanone
L/40" must not be less than $300,000 or $400,000. Now, on the interest of
such a sum we could have from ten to fifteen complete batteries, that is to
say, comprising, in addition to the sixty or eighty guns, all the necessary
accessories, such as carriages, limbers, caissons, harness, etc.

Frankly, between the two acquisitions, there is no hesitation possible.

Finally, if we must say so, we do not think that foreign powers, when they
believe it their duty to provide themselves with _materiel_ of great
caliber, will think of supplying themselves from the Essen works, on
account of the memorable accidents due to the imperfection of guns coming
from this celebrated establishment. The list of burstings that have
occurred, not only in Germany, but also in Russia, Bohemia, Italy, Turkey,
and Roumania, is already a long one. To speak here only of what occurred
in France in 1870-71, it is certain that out of seventy German guns of
large caliber in battery against the southwest front of the wall of Paris,
thirty-six--say more than half--were put out of service during the first
fifteen days of the bombardment, and that too through firing merely; and it
was the opinion of Mr. De Moltke himself that the German siege batteries
would have been reduced to silence, had the defenders been able to hold out
for a week longer. It is equally certain that, during the course of the
Loire campaign, eighty guns of Prince Frederick Charles' were put out of
service by the sole fact of their firing. Summing up the history of these
many accidents, the Duke of Cambridge asserted to the House of Lords (April
30, 1876) that _two hundred_ Krupp guns burst during the Franco-German war.
Have the engineers of the Essen works improved their processes of
manufacture since that epoch? It is permissible to doubt it, seeing that,
very recently, the Italian navy refused to take from Mr. Krupp some 15½
inch guns whose tubes were but very imperfectly welded.

Must the numerous accidents mentioned be attributed to defects in the metal
employed? Were they due to defective hooping? Were they due to some one of
the numerous inconveniences inherent to the cylindrico-prismatic system of
closing (_Rundkeilverschluss_)?

They were doubtless owing to such causes combined.--_La Nature_.

       *       *       *       *       *




COLORS OF THIN PLATES.


The Right Hon. Lord Rayleigh lately delivered a lecture at the Royal
Institution upon "The Colors of Thin Plates," a term which he explained was
applied to thin films of substances, such as oily films on the surface of
water or the equally familiar soap bubble. Although the reflection of
colors from the surface of a soap bubble is probably the most noticeable,
yet the "plate" which lends itself most readily for experiment is a film of
air confined between two sheets of glass. If a ray of white light be
reflected from the surface of the film upon a screen, the so-called
Newton's rings, a series of colored concentric rings, are obtained. If,
instead of reflected light, the ray of light transmitted through the film
of air be allowed to fall upon the screen, the same phenomenon is
observable, but the effect is very considerably minimized, owing to the
great preponderance of white light, which overlies as it were the colored
rings. Even in the first instance, as the lecturer was able to show later
on, the colors are not nearly so intense as they may be obtained, owing to
some white light being reflected from the surfaces of the two sheets of
glass. With regard to the appearance of the phenomenon, it is observed that
the part which corresponds to the thinnest part of the film is considerably
darker than the rest of the spectrum; around this is a bright ring of
white, succeeded by constantly increasing concentric rings of different
colors apparently repeating themselves. Lord Rayleigh also obtained the
same results with a film of a solution of soap and glycerine, but in this
case the dark portion was observed at the top of the spectrum, the other
colors arranging themselves in order in the soap film thinned by the force
of gravitation, thus showing that the colors vary according to the
thickness of the film. Another form of the experiment called forth a
considerable amount of applause from the audience. Lord Rayleigh caused a
gentle stream of air to play obliquely upon a soap film, so that the part
struck was moved forward and the whole film rotated. Then with the
alteration of the force of the current of air, which of course regulated
the centrifugal force, alternating thicknesses of film were obtained,
causing a varying display of beautiful colors and combinations of colors.
This last experiment also tended to prove that the bands of color are not
arranged in a certain order, but vary according to the thickness of the
film, a conclusion arrived at by Brewster, who observed that if a film
reflecting certain colors be carefully inverted so as not to disturb the
gravity, the colors reflected are also inverted. Lord Rayleigh explained
the phenomenon by referring to Young's wave theory of light. He regarded
the film as having two surfaces from which light is reflected, an anterior
exterior surface and a posterior interior surface. If a ray of light be
thrown upon the film, a part of the light is reflected from the first
surface, but the greater part is transmitted, and some of this is reflected
from the second surface, passes back through the film, and is combined with
the light reflected from the first surface. If then the light reflected
from the second surface be in the same state of vibration as that reflected
from the first surface, the effect of their combination will be to increase
the amount of light reflected from the first surface, but if otherwise, the
effect will be a partial neutralization of the light reflected from the
first surface. That is to say, if the retardation of the light which is
reflected from the second surface, owing to its twice traversing the
thickness of the film, be equivalent to a wave length of the vibration of
the light, it will increase the intensity of the light reflected from the
first surface. If, however, the retardation be only equivalent to half a
wave length, the intensity of the light will be decreased. Thus, then, with
a ray of monochromatic light it will be seen that the effect of difference
in the thickness of the film will be to alter the intensity of the
reflected ray, but with a white light composed of several colors the result
will be more complicated. As each color has a different wave length in
vibration, it will be seen that each color will act independently of the
others, and a certain thickness of film which, upon the combination of the
two reflected rays, will cause one particular color to be intensified, will
at the same time cause the other colors to be more or less obscured.

Thus as the thickness of the film is altered different colors preponderate,
causing the appearance of rings or bands, according to the nature of the
experiment. The dark appearance on the screen corresponding to the thinnest
part of the film is probably due to refraction of the ray of light
reflected from the second surface, consequent in its passing from a rare
into a denser medium, and again from the denser medium into the rare, which
refraction Lord Rayleigh considers to effect a retardation equivalent to
half a wave length. Lord Rayleigh supported this theory of the formation of
Newton's rings by several interesting experiments. A beam of light was
intercepted by two of Nicol's prisms, one of which acted as a polarizer and
the other as an analyzer of the light, so that no light was able to pass
through both on to the screen. Between the two prisms a double refractive
lens was now placed, in this case a double concave lens of selenite, when
the same series of concentric rings observed with the film of air was
obtained on the screen, only much more intense, while a wedge of selenite
gave the bands of color in the same order as with the soap bubble.

But perhaps the most striking proof of the dependence of the colors upon
the thickness of the film was shown by the reflection of a beam of light
from a piece of mica composed of twenty-four very attenuated plates
overlapping each other. With each layer a marked gradation in color was
visible.

The remainder of the lecture was devoted to an explanation of the
determination of the chromatic relations of the colors of the spectrum.
Lord Rayleigh at this point made a rather startling statement that any
color can be produced by two other colors. As an example of such a
formation, a ray of white light was passed separately through a solution of
yellow chromate of potash and an alkaline litmus solution, throwing
respectively a yellow and violet-blue color upon the screen. When the ray
was made to pass through the two solutions successively, an orange-yellow
color was obtained upon the screen, which color Lord Rayleigh asserted to
be made up of red and green rays. To prove this, the ray of white light was
decomposed by means of a prism, and the decomposed rays passed through the
two solutions. The one solution was found to exclude all the yellow and
orange rays from the spectrum, while the other excluded all the blue and
violet rays, so that when the ray had passed through both solutions, only
the red and green rays were left. If, instead of allowing the decomposed
ray of light to pass through a slit, and thus obtain definite bands in the
spectrum, the ray was passed through a circular hole, the red and green
colors overlapped each other on the screen, forming by their combination
the identical orange-yellow color obtained with the primary white light. It
was then stated that if three definite positions be taken in a spectrum in
the red, green, and violet bands respectively, and these positions be
represented by the corners of an equilateral triangle (Clerk Maxwell's
triangle), it has been mathematically determined in what position within
this triangle the colors of Newton's rings would fall. Lord Rayleigh, by
means of a diagram and the selenite wedge, showed that the relations to the
three standard colors in practice were identical with the position assigned
them by theory.

In conclusion, the lecturer showed a piece of glass, the surface of which
had been decomposed, a ray of light transmitted through which showed upon
the screen patches of very pure color. These he considered to be due to the
glass consisting of a number of thin plates, some of which had been removed
by the decomposition.

       *       *       *       *       *




BELT JOINTS.


From time to time, serious accidents have taken place, and the progress of
work stopped, by the sudden snapping of driving belts in machinery, and, as
a general rule, it is found that the collapse is attributable either to
faulty leather or insecure joining. A great improvement of the leather
intended for belts has been brought about during the last few years, by the
introduction of improved processes for currying and the subsequent
treatment. Paterson has worked successfully a patent for rendering belt
leather more pliable, and lessening the tendency to stretch. Under this
treatment the leather is either curried or rough dried, and then soaked in
a solution of wood, resin, and gum thus, or frankincense, first melted
together, and then dissolved, by the application of heat, in boiled or
linseed oil. The leather, after this process, is soaked in petroleum or
carbon bisulphide containing a little India-rubber solution, and is finally
washed with petroleum benzoline. Should the mixture be found to be too
thick, it is thinned down with benzoline spirit until it is about the
consistency of molasses at the ordinary temperature. The leather so
prepared is not liable to stretch, and can be joined in the usual way by
copper riveting, or the ends can be sewn. A good material for smaller
belts, and for strings and bands for connecting larger ones, is that
recently patented by Vornberger, in which the gut of cattle is the basis.
After careful cleansing, the gut is split up into strands, and treated with
a bath of pearlash water for several days. The strands are then twisted
together, and after being dipped in a solution of Condy's fluid, are dried.
They are then sulphured in a wooden box for twenty-four hours, after which
the twisting can be completed. They are by this process rendered pliable,
and can be used in this state for stitching the leather ends of larger
belts, or can be stiffened by plunging them into a bath of isinglass and
white wine vinegar. After drying they are susceptible of a fine polish,
emery cloth being usually employed, and the final "finish" is given to the
material with gum arabic and oil.

Canvas and woven fabrics, coated with India-rubber, are also now being used
for driving belts and for covering machine rollers. As this material can be
made in one piece, without the necessity of a joint, it is uniform in
strength, and is recommended as a substitute for leather belts requiring
joints. A patented material of this description is due to Zingler, who
boils the canvas or similar woven fabric under pressure in a solution of
tungstate of soda for three hours. It is then transferred to a bath of
acetate of lead solution, and drained, dried, and stretched. When in this
condition it is coated, by means of a spreading machine, with repeated
layers of a composition consisting of India-rubber, antimony sulphide,
peroxide of iron, sulphur, lime, asbestos, chalk, sulphate of zinc, and
carbonate of magnesia. When a sufficient thickness of this composition has
been applied, it is vulcanized under pressure at a temperature of 250° F.,
or a little higher. The material produced in this manner is said to have
the strength and durability of the best leather belts. Attempts have
recently been made to obtain a glue suitable for joining the ends of
driving belts, without the use of metal fastenings or sewing, and Messrs.
David Kirkaldy & Son have reported favorably on such a belt glue, which is
being introduced by Mr. W.V. Van Wyk, of 30 and 31 Newgate street, E.C. In
the test applied by them, a joint of this "Hercules glue," as it is called,
in a 4 in. single belt was stronger than the solid leather. When a tensile
stress of 2,174 lb., equivalent to 2,860 lb. per square inch of section,
was applied, the leather gave way, leaving the joint intact. Belts
fastened by a scarf joint with this glue are said to be of absolutely the
same thickness and pliability at the joint as in the main portion of the
belt, and thus insure freedom from noise and perfect steadiness. The
instructions for use are simple, and it requires only fifteen minutes for
the joint to set before being ready for use. From a rough chemical analysis
of the sample submitted to us, we find that it consists of gelatine, with
small amounts of mineral ingredients. Josef Horadam, some few years ago,
patented in Germany a process for preserving glues from decomposition, by
the addition of from 8 to 10 per cent. of magnesium or calcium chlorides.
The addition of these salts does not impair in any way the strength of the
glue, but prevents it from decomposing, and it may be that the "Hercules
glue" is preserved in a similar manner.

A cement of this nature, if thoroughly to be relied on, must be of great
value, although the great variation in the quality of leather, apart from
the difficulty hitherto experienced of securely connecting the ends
together, opens a wide field for a material of uniform composition, and
capable of being made in one piece in suitable lengths for driving belts
and other machine gear.--_Industries._

       *       *       *       *       *




INAUGURATION OF THE STATUE OF DENIS PAPIN.


A large crowd was present recently at the inauguration of the statue of
Denis Papin, which took place in the court of the Conservatoire des Arts et
Metiers, under the presidency of Mr. Lockroy, Minister of Commerce and the
Industries.

[Illustration: DENIS PAPIN.]

In the large hall in which the addresses were made there were several
municipal counselors, the representatives of the Minister of War, Captains
Driant and Frocard, several members of the Institute, and others. A
delegation from the Syndical Chamber of Conductors, Enginemen, and Stokers,
which contributed through a subscription toward the erection of the statue,
was present at the ceremony with its banner. Mr. Lanssedat, superintendent
of the Conservatoire, received the guests, assisted by all the professors.
Mr. Lanssedat opened the proceedings by an address in which he paid homage
to the scientists who were persecuted while living, to Denis Papin, who did
for mechanics what Nicolas le Blanc did for chemistry, and to those men
whose entire life was devoted to the triumph of the cause of science.

After this, an address was delivered by Mr. Lockroy, who expatiated upon
the great services rendered by the master of all the sciences known at that
epoch, who was in turn physician, physicist, mechanician, and
mathematician, and who, in discovering the properties of steam, laid the
foundation of modern society, which, so to speak, arose from this
incomparable discovery.

Speeches were afterward made by Mr. Feray d'Essonnes, president of the
Syndical Chamber of Conductors, Enginemen, and Stokers, and by Prof.
Comberousse, of the Central School, who broadly outlined the life of Papin.

Along about four o'clock, the Minister of Commerce and the Industries,
followed by all the invited guests, repaired to the court, and the veil
that hid the statue was then lifted amid acclamation.

Papin is represented as standing and performing an experiment.

Upon the pedestal is the following inscription:

    DENIS PAPIN
    BORN IN 1647, DIED ABOUT 1714,
    INVENTED THE STEAM ENGINE
    IN 1690

    NATIONAL SUBSCRIPTION, 1886.

The inauguration is due to the initiative of Mr. Lanssedat, for it was he
who in 1885 suggested the national subscription, which was quickly raised.

Denis Papin was born at Blois on the 22d of August, 1647. He was the son of
a physician. After the example of his father and of several of his
relatives, he studied medicine and took his degree; but his taste for
mathematics, and especially for experimental physics, soon led him to
abandon medicine.

It was in 1690 that he published in the _Actes_ of Leipsic the memoir which
will forever and irrevocably assign to him the priority in the invention of
steam engines and steamboats, and the title of which was: "New method of
cheaply obtaining the greatest motive powers."

In 1704, Papin, poor and obliged to do everything for himself, finished his
first steamboat; but for want of money he was unable to make a trial of it
until August 15, 1707. The trial was made upon the Fulda and Wera,
affluents of the Weser.

The operation succeeded wonderfully, and, shortly afterward, Papin, being
desirous of rendering the experiment complete, put his boat on the Weser;
but the stupid boatmen of this river drew his craft ashore and broke it and
its engine in pieces.

This catastrophe ruined Papin, and annihilated all his hopes. The great
man, falling into shocking destitution, broken down and conquered by
adversity, returned to England in 1712 to seek aid and an asylum.

Everywhere repulsed, he returned to Cassel about 1714, sad and discouraged;
and the man to whom we owe that prodigy, the steam engine, that instrument
of universal welfare and riches, disappeared without leaving any trace of
his death.--_Le Monde Illustre._

       *       *       *       *       *




DECORATION.

THE STUDY OF ORNAMENTS.

[Footnote: _Authorities consulted in preparing this paper:_ "Analysis of
Ornament," Wornum; "Truth, Beauty, and Power," Dresser; "Lectures on Art."
F.W. Moody; "Hopes and Fears for Art," Wm. Morris; "Ornamental Art," Hulme;
"Manuals of Art Education," Prang.]

By MISS MARIE R. GARESCHE, St. Louis High School.


Decoration is the science and art of beautifying objects and rendering them
more pleasing to the eye. As an art, individual taste and skill have much
to do with the perfection of the results; as a science, it is subject to
certain invariable laws and principles which cannot be violated, and a
study of which, added to familiarity with some of the best examples, will
enable any one to appreciate and understand it, even if lacking the skill
and power to create original and beautiful designs.

The study of decoration offers many advantages. It cultivates the
imagination and the taste; it develops our capacity for recognizing and
enjoying the beautiful in both nature and art; it adds to the pleasure and
refinement of life. Practically, its importance can hardly be
overestimated, as it enters into almost all the industrial pursuits. We can
think of but few classes of objects, even the most simple, in which some
attempt at ornamentation is not made.

Ornament is one of the principal means of enhancing the value of the raw
material. A piece of carved wood, or an artistically decorated porcelain
vase, worth perhaps many hundred dollars, if reduced to the commercial
value of the material of which they are composed would be valued at but a
few dollars or cents. The higher the ornamentation ranks, from an artistic
point of view, the greater becomes the value of the article to which it is
applied. Knowledge of good designs is thus evidently important, to the
purchaser of the object ornamented as well as to the designer who planned
it. This can only be attained by cultivation.

To know and appreciate the best ornament should be an aim set forth in any
scheme of general education. This knowledge and appreciation can be
obtained by studying the application of the laws and principles of
ornamental art as exemplified in the works of masters, and also by
endeavoring to apply these principles in designs of our own creation.


PRINCIPLES OF ORNAMENT.

We can only arrive at a knowledge of these principles by a consideration of
the object. In other words, nature and history must be studied. First,
_nature_, for she is the primary source and origin of all good ornament,
whether ancient or modern; and if, as in everything else, we would not
become servile imitators and weak copyists, we must go to the fountain
head. Second, _history_, for by the study of the ornament of past ages we
will not only become acquainted with the highest developments of which
ornamental art is capable, but will moreover broaden our views as to its
object and scope, and will stimulate our own imagination and invention, by
leading us to the contemplation of the myriad beautiful and protean forms
it has assumed, when surrounding conditions, such as religion, climate,
temperament, nationality, etc., have been different. Knowledge of historic
ornament will also prevent the imposition on the public, so common in our
day, of weak and unworthy productions which claim to be based on classic
originals, and which constitute a great stumbling block to the progress and
appreciation of good art. The result is somewhat analogous to that produced
upon conscientious but ill-informed minds, who make every effort to
appreciate and enjoy the spurious productions of a great author, not
knowing that they are not genuine.


POSITION AND SCOPE OF ORNAMENTAL OR DECORATIVE ART.

I. _Object of Ornamental Art._--The object or purpose of ornament, as in
the other fine arts, is to please. In music and poetry this enjoyment is
conveyed to the mind through the ear; in the decorative and pictorial arts,
through the eye. Generally, the meaning that we find in such productions,
the appeal that they make to the understanding or feelings, is as great a
source of interest to us as their intrinsic beauty. Poetry and vocal music
are greatly dependent for their effect upon the meaning they convey in
words; painting and sculpture, upon the ideas or sentiments they suggest.
In all four, however, and most decidedly in music unaccompanied by words,
the appeal is frequently made almost exclusively to the æsthetic sense, the
mind or intellect remaining almost dormant under the impression. Gems of
rhythmical verse, such as Poe's "Bells," "The Raven," Whistler's
"Symphonies in Color," nameless forms in statuary, expressionless save in
the mere beauty of their proportions and curves, and, as has been stated,
nearly the entire field of instrumental music, are cases in point. In the
ornamental and decorative arts, as well as in architecture (from which they
are indeed inseparable), beauty alone, in like manner, should be the
principal aim and purpose. In the former, of course, it is indispensable
that such should be the case, as they are entirely subordinate and
accessory in their nature, their only _raison d'etre_ being to beautify or
render more agreeable objects already created for some purpose.

It must not be imagined that such artistic impressions--viz., where the
appeal is made almost solely to the æsthetic sense, regardless of the
reason, judgment, or feelings--are necessarily of a lower order. Their
effect is almost analogous to that which nature herself produces upon
us--the starry heavens, the mighty ocean, the tender flower. The
impression, whether the object belongs to the domain of nature or art, may
be a merely sensuous one; and if it stops there, as it certainly does for
the majority of people, it ranks without doubt far below productions where
the æsthetic element is only used to stimulate and heighten the appeal to
the mind or the feelings. But if it extend beyond, and makes the sensuous
impression but the parting link to the contemplation of ideal, abstract
beauty, without the intermediate aid of the heart or the reason, it is the
shortest and quickest road toward the realization of the infinite, and
makes us indeed feel that it is but a short step "from nature up to
nature's God." Thus architecture, which embodies, more than any other of
the space arts, principles of abstract beauty, has been with reason called
the noblest of them all.

However, ornamental and architectural forms frequently do convey a meaning,
which we term symbolism in art. If this symbolism does not detract from the
first object of ornament--viz., to beautify--it is perfectly legitimate and
proper. It is impossible to fully appreciate many phases of art, as, for
instance, the Egyptian and the early Christian, if we leave out of sight
the symbolism which pervades them.

While beauty, or capacity for pleasing the eye, may be very definitely said
to be the aim of ornamental art, it is difficult to arrive at a universal
standard as to what constitutes beauty. What pleases one person will not
always please another. The child loves glittering objects and gaudy
combinations, which the mature taste of the man declares extravagant and
unharmonious. Savages decorate their weapons, utensils, and their own
persons with ornaments that appear uncouth and barbarous to civilized
people.

Besides these differences in taste, which are due to different degrees of
mental development, and which can consequently be easily disposed of, we
find among highly civilized and cultured nations, at different periods, a
great diversity of tastes. These varying and sometimes apparently
conflicting products of ornamental art we designate as styles, viz.,
Egyptian style, Greek style, Gothic style, etc. So marked are the
differences between them that we can sometimes tell at a glance to what
period and to what style a small fragment of decoration belongs.

Notwithstanding these differences, which at first may appear very great, a
careful study of the best styles--those that achieved the greatest and most
lasting popularity--will reveal the fact that they are all based upon
certain fundamental laws and principles, and that all are good, bad, or
indifferent according as they conform to or violate these principles. These
essentials having been preserved, the opportunities for the exercise of
individual or national taste are almost boundless.

II. _Position of Ornament._--The position that ornament occupies is
necessarily a secondary one, as it cannot exist independently, but is
always applied to objects created for some purpose entirely independent of
their capacity for pleasing. This gives us one of the great underlying
principles that should characterize all ornament, viz., _it must be
subordinate to the object which it adorns, and must not detract from its
use_. We often see this rule violated in personal, household, and
architectural decoration--windows so overloaded with projecting cornices
and lattice work as to almost exclude light and air; knife handles carved
so elaborately that it is impossible to grasp them firmly; styles of dress
in form or color that impede the motions of the wearer, and make the
clothes, rather than the personality of the wearer, the most noticeable
feature. From this principle there is but a step to another: _All ornament
should be modest and moderate_. It must not obtrude itself, and a great
profusion and ostentation in its application is always a sign of degeneracy
and bad taste. Of course some objects, from their nature, position, and
use, will admit of greater and more elaborate ornament than others.

Ornament, being entirely subordinate, should not conceal the construction
of the object. In architecture it should follow the leading lines of the
building, and should emphasize, or at least suggest, the construction. If
architectural in character, it should so enter into the construction of the
building that it could not be taken away without injuring it.

We must feel that a column, no matter how beautiful, is supporting
something. A floor, always a plane surface, must not be tiled or decorated
in any way to express relief. This would apparently destroy the essential
constructive quality of a floor, viz., flatness. For the same reason, all
shams, such as painted arches, pillars, etc., are not legitimate. As long
as they do not actually exist, they are evidently not necessary to the
construction, and have no purpose save an imaginary decorative one, and in
the words of Owen Jones, _construction must be decorated--not decoration
constructed_.

III. _Scope of Ornament._--The scope of ornamental art is almost boundless.
It is applied to objects large and small, adapted to the most various uses,
constructed of the most different materials. As the ornamentation is always
to be subordinate to the object, considerations regarding size, use,
position, material, etc., must govern it. An ornament that would be
admirable applied to one object, might be detestable if applied to another.
A design cannot be made without reference to its future application.

First: The material must be considered. Heavy and hard materials, such as
wood and stone, will not admit of as delicate curves and lines as textile
fabrics, such as cotton and woolen goods, laces, etc.

Second: The manner in which the article is to be made, whether by weaving,
cutting, carving, casting, etc.

Third: The position the object is to occupy. If elevated or otherwise
remote from the eye, elaborate finish and minute detail are useless.
Ornamental art, from time immemorial, has attained its greatest excellence
and exercised its greatest influence in connection with architecture.

In fact, the study of ornament is inseparable from that of architecture. It
is upon architectural forms that the greatest artists have in all ages
expended their greatest efforts and skill, and in a treatise on historic
ornament they are decidedly the most interesting and important object of
study.

IV. _Material of Ornament._--The two great sources of ornament are geometry
and nature. The latter includes the former; for not only must natural
forms, in order to be available as material for ornament, be first
conventionalized, or reduced to regular, symmetrical, geometric outlines,
but any and all designs, whether the unit of repetition be geometric or
conventional, must be founded upon geometric construction. This refers to
the regularity, repetition, and distribution of parts; so that every good
design, if reduced to its principal lines of construction, would exhibit
but a few geometric lines and inclosing spaces. Many designs are not only
geometric in their basis or plan, but make use of geometric figures as the
units or materials of design. Such designs, however, rank lower than those
in which natural forms conventionalized are taken as the subjects of
repetition; and as the ornament rises in the scale toward perfection, even
the geometric basis becomes less and less apparent, and sinks into a
decidedly subordinate position; so that in many of the most perfect
specimens it can be traced only in a few leading lines of the composition.
Its presence, however, is necessary, and is the foundation, if not the most
important element, of beauty in the design.


RELATION BETWEEN NATURE AND ORNAMENTAL ART.

While the natural world, including leaves, flowers, animals, etc., is the
greatest source of ornament, it is generally the opinion of the best
authorities, derived from the study of the best styles and by a
consideration of the principles of fitness and propriety which underlie the
entire physical and moral world, that natural forms in ornamental and
decorative art should not be literally copied or imitated. That is the aim
of painting, sculpture, and the other representative arts, where the object
is to present something to the eye which will suggest at once the actual
presence of the object. To produce that effect, the object, whether animal
or vegetable, is represented as much as possible in the actual
circumstances of its existence, surrounded by the necessary conditions of
its well-being and growth. A frame is placed around it, to shut it off as
much as possible from other surroundings, and thus help us delude ourselves
that we are in the presence of the real thing, either as it would impress
us through our senses or our imagination.

But in ornamental art the case is entirely different. As it is to be
applied and consequently subordinated to something, and does not exist for
itself, it would be impossible, except in very rare instances, to introduce
in a design a natural object in a realistic manner and not violate some
important law of its growth or the conditions of its well-being. For
instance, to exactly repeat a certain rose, with all the accidents of its
growth, many times in a carpet is not natural. Nature never repeats
herself. Moreover, to tread on that which is supposed to suggest to us real
roses is barbarous. It would really be outraging and distorting nature
while pretending to be her faithful disciple and imitator.

We not only derive from nature the most important materials for our
designs, but also the various modes of arranging this material. Various
modes of repetition--radical, bilateral, etc.--were all probably suggested
by some natural arrangement observed in flowers, leaves, etc. Of these
different arrangements it is curious to note that the bilateral is more
characteristic of the higher forms of nature and the radiating of the
lower. The leading principles of ornament--symmetry, proportion, rhythm,
contrast, unity, variety, repose, etc.--are all exemplified in natural
forms. The latter have also suggested many of the most important
architectural forms. The Gothic cathedral, with its clustered columns
branching and forming pointed arches overhead, was probably suggested by a
grove of trees with overarching branches and boughs. The idea of the column
was derived from the papyrus plant, a species of reed growing in the river
Nile. The bud or flower suggested the capital of the column; the stalk, the
shaft; and the bulbous root, the pedestal. The blue vault of the sky
undoubtedly suggested the dome, etc.

The following are a few of the leading principles of ornamental art as set
forth by Owen Jones in his _Grammar of Ornament_, a fine work,
magnificently illustrated, whose perusal could hardly fail to delight the
most indifferent:

"All good ornamental art should possess fitness, proportion, harmony, the
result of all which is repose."

"Construction should be decorated. Decoration should never be purposely
constructed."

"All ornament should be based upon geometrical construction."

"Harmony of form consists in the proper balancing and contrast of the
straight, the inclined, and the curved."

"In surface decoration all lines should flow out of a parent stem. Every
part, however distant, should be traced to its branch or root. Natural
law."

"All junctions of curved lines with each other, or with straight lines,
should be tangential to each other. Natural law."

"Natural forms, as subjects of ornament, should not be imitated, but should
be conventionalized."


HISTORIC ORNAMENT.

The origin of all attempts at decorating or beautifying objects lies in the
universal love of mankind for the beautiful. Once the necessaries of life
provided for, man instinctively, the world over, turns his attention toward
gratifying this feeling, by improving and decorating the forms around
him--his arms, utensils, dwelling, or his own person. The history of every
nation proves this, and no matter how rude, and even ugly, their efforts
may seem to us, we are bound to recognize in them the same motives that
actuated the builders of the Parthenon or of St. Peter's at Rome. This
awakening and gratification of the æsthetic sense seems to be the first
advance from a condition of mere animal existence, in which food, shelter,
and comfort are the only considerations, to tastes and desires that are
higher and, consequently, more impersonal.

The term historic ornament is applied to the various styles of ornamental
art which have flourished at various periods in the world's history, from
the Egyptian, dating from the 14th century B.C., to those that exist at the
present day. Their number is, consequently, almost unlimited, and we will
confine ourselves to the consideration of a few of the principal ones
only--those that have achieved the most enduring fame, or those that
exercised the most marked influence upon succeeding styles.

In considering the various styles, we must always bear in mind that, with
the exception of the Egyptian, all show very markedly the influence of the
styles that preceded them, being very often merely an outgrowth or
development of a preceding one. Thus the Greeks borrowed many forms from
the Egyptians. The Romans simply adapted and elaborated the Greek style,
etc. So that while each style is usually known by certain prominent
characteristics, it does not follow that these characteristics are peculiar
to it alone.[1] They may be found in other styles, though not to such a
great extent. While similar features will thus be seen to run through many
styles, each will usually be found to possess an individuality of its own.
Every nation, like every individual, possesses different wants and
capabilities, and will develop itself accordingly. Differences in religion,
climate, manners, customs, etc., will cause differences in their art and
literature, the most lasting monuments of their morals, taste, and
feelings.

[Footnote 1: "Rudiments of Architecture and Building," through courtesy of
H.C. Baird.]

It is rather by the study of the art and literature of a people that we
arrive at a true knowledge of them than from the perusal of mere historic
facts concerning them--when they lived, who conquered them, etc.


THE STYLES.

ANCIENT OR CLASSIC. 1400 B.C.--300 A.D.

    _Egyptian._--Characteristics: symbolic, severe,
        simple, grand, massive. Conventional forms of lotus,
        papyrus, etc. Oblique lines.

    _Greek._--Characteristics: æsthetic, simple,
        harmonious, beautiful. Conventional forms, anthemion,
        acanthus. Ellipse.

    _Roman._--Characteristics: elaborate, rich, costly.
        Conventional forms, acanthus scroll, monsters. Circle.

MEDIEVAL. 300 A.D.--1300 A.D.

    _Byzantine._--Symbolic, rich, elaborate. Conventional
        forms, principal architectural feature--dome.

    _Saracenic._--Gorgeous coloring, graceful curves.
        Forms entirely geometric. Arabesque, geometrical
        tracery, interlacing.

    _Gothic._--Imposing, grand. Pointed arches, clustered
        columns, vaulted roof, spire buttress. Forms both natural
        and conventional. Stained glass.

MODERN OR RENAISSANCE. 1300 A.D.--1900 A.D.

    _Renaissance._--Mixture of classic and mediæval
        elements. Result not generally good.

    _Cinquecento._--Æsthetic, revival of true classic
        principles. Beautiful curves, fine proportions
        and distribution. Conventional animal and plant
        forms. Human figure.

    _Louis Quatorze._--Sparkling, glittering. Absence
        of color, want of symmetry.


I. ANCIENT OR CLASSIC ART.

Ancient art is also known as classic, a term which, in architecture,
sculpture, painting, and music, is almost synonymous with _good_ and
_admirable_. Taken as a whole and at its best, classic art has never been
surpassed. The designs of the Greeks, Romans, and Egyptians, and even the
forms of their buildings, are still copied at the present day.

The horizontal line is a marked feature of classic art. It is visible in
the leading lines of their architecture, in the frequency of horizontal
borders, friezes, etc. It accords admirably with the constructive features
of classic architecture, and thus conforms to the important decorative
principle that ornament should emphasize rather than disguise construction.

1. _Egyptian Art._--The oldest of which we have any record dates from 1800
B.C. Egyptian art is symbolic, that is to say, the forms were chosen not so
much on account of their beauty as for the purpose of conveying some
meaning. The government of Egypt being almost entirely in the hands of the
priests, these symbols were generally of a religious character, signifying
power and protection. The principal ones were: The lotus, signifying
plenty, abundance; the zigzag, symbolic of the river Nile; the winged globe
or scarabæus, signifying protection and dominion, usually placed over doors
of houses; the fret, type of the Great Labyrinth, with its three thousand
chambers, which was, in its turn, symbolic of the life of a human soul.

The column originated with the Egyptians. It was at first heavy, broad
compared to its length, and was usually covered with hieroglyphics. The
architecture of Egypt, of which the principal forms are pyramids, sphinxes,
obelisks, and temples, is characterized by massiveness of material,
grandeur of proportion, and simplicity of parts--a style well suited to its
flat, sandy soil, though it would look heavy and out of place in a country
where nature had herself supplied the elements of grandeur and massiveness
in the form of lofty mountains or mighty forests. Egyptian art greatly
influenced all the succeeding styles, and to this time is unsurpassed in
many of its qualities.

2. _Greek Art._--The next great historic style is the Greek. Its spirit
differed entirely from the Egyptian, being æsthetic and not symbolic. Its
sole aim was to create beautiful forms, without any thought of attaching to
them a meaning. It adopted many Egyptian forms, such as the lotus, fret,
and scroll, but divested them of all symbolism or significance. The most
characteristic feature of Greek ornament is the anthemion, a
conventionalized flower form resembling our honeysuckle bud, which was
usually alternated with the lotus or lily form bud. The Greeks also
borrowed the column and flat arch from the Egyptians, but changed it to a
more slender, graceful form. The three principal orders of Greek
architecture are named from the style of the column used that characterized
them, viz., the Corinthian, the Doric, the Ionic. Of these the Doric is the
simplest and the Corinthian the most elaborate.

For harmony of proportions, elegance of form, and simplicity of detail,
Greek architecture and ornament has probably never been surpassed. These
qualities are admirably displayed in the Parthenon, a temple in Athens,
dedicated to Venus. Though in ruins, it is still one of the greatest
attractions to travelers in Greece. A very fine collection of fragments
taken from it is to be seen in the British Museum. They are known as the
Elgin marbles.

The most flourishing period of Greek art, as will be found in the history
of almost all nations, was identical with the most flourishing period of
its literature and general welfare.

3. _Roman Art._--In the 6th century B.C. the Greeks, already on the
decline, were conquered by the Romans, a nation hardier and more powerful,
though ruder and less civilized than themselves. The conquerors recognized
this, and immediately set to work to copy or steal from their vanquished
foes everything that might enhance the beauty and splendor of their own
city. Greek artists were transported to Rome and placed in charge of the
most important public works. Roman art is, consequently, but a development
or adaptation of the Greek. It is noticeable, however, that it almost
completely ignored the most characteristic and popular of the Greek
forms--for example, the anthemion--and adapted those, such as the acanthus
and the scroll, which had been considered of minor importance among the
Greeks. They added another to the three orders of the Greek architecture,
viz., the Composite, the most elaborate of all, being a combination of the
Ionic and the Corinthian. This leads us to consider the leading features of
Roman ornament--richness and profusion. With the acanthus and scroll as
their principal units of design, they elaborated and enriched every form
that would admit of it. The most elaborate Greek example cannot compare in
this respect to the simplest Roman. The Roman style of architecture was
very similar to the Greek, though more massive in its proportions, probably
on account of the larger number of people to be accommodated. The details
were also bolder and the curves fuller. They used the round arch to a great
extent. The column of Trajan and the Forum are fine examples of their
architecture.


II. MEDIÆVAL ART.

The Roman empire, after having reigned as mistress of the world for upward
of five centuries, commenced to show signs of decay. Its people had
gradually lost the sturdy spirit of independence, endurance, and courage
which had characterized their forefathers, and had degenerated into a race
of effeminate slaves and cowards. Ostentation became the feature of their
art; immorality and luxury, of their mode of living. They thus fell an easy
prey to the rude but vigorous barbarians of the North. The latter, rude and
uncivilized as they were, extended the contempt they had for the nation
they had conquered to their works of art as well, and mutilated or
destroyed them whenever they could lay hands on them.

This spirit of antagonism was strengthened upon their conversion to
Christianity, and everything that savored of paganism in art or literature
was severely proscribed. For the heathen forms, whose only aim and object
was beauty, were substituted religious symbols, the cross and other
implements of the passion, the lily, the fish, the aureole, etc., whose
object was to recall to the faithful the mysteries of religion. Gradually,
however, as the artistic feelings of the new people became awakened,
principles of beauty commenced to be regarded, and, while symbolism
remained an important feature of European art until the period of the
Renaissance, and even then was not entirely superseded, magnificent
artistic results were obtained.

1. _Byzantine Art._--The principal of the early mediæval art developments
was the Byzantine. It flourished principally in the eastern part of Europe.
In the west it was known, with a few variations, as the Lombard and the
Norman. All three are often included under the term Romanesque.

Byzantine art was essentially Christian in its spirit and motives. It used
religious symbols extensively, but incorporated in its ornament a few pagan
elements, such as the acanthus and the scroll. Natural forms were always
conventionally treated. Its coloring was rich and gorgeous. The principal
features of its architecture were the dome and round arch. The plan of the
churches was often in the form of a Greek or Latin cross, with the dome
placed over the intersection of the two arms. The church of St. Sophia, in
Constantinople, is the most magnificent example of Byzantine architecture
and ornament. Although now a Mohammedan mosque, it is, probably, in the
motive and spirit that actuated its construction, the most Christian
building in the world.

2. _Saracenic Art._--Developed from the Byzantine by the Moors and the
Saracens. It differs from it, however, in one important respect. While the
Byzantine makes use of numerous conventionalized plant and animal forms,
the Saracens and Moors were forbidden by their religion, the Mohammedan, to
copy in any manner the form of any living thing, animal or vegetable. They
were thus limited entirely to geometric forms, which, however, often fall
insensibly into flower and leaf forms. Interlacing bands and curves of
intricate pattern, and exhibiting the peculiar Moorish curve, are very
characteristic of Saracenic ornament. Inscriptions were frequently
interwoven in this tracery.

The coloring was gorgeous, consisting principally of blue, red, and gold.

The principal arches used were the pointed and the horseshoe arch. The
Alhambra Palace in Spain is the most famous example of Saracenic ornament
and architecture.

3. _Gothic Art._--Gothic art grew out of the Byzantine, all the symbolic
elements being retained. It is divided into many different varieties.

In the earliest the round arch was used, but the later and more perfect
styles having employed the pointed arch almost exclusively, the latter
became characteristic of Gothic art generally. It is a style of
architecture and ornament usually applied to churches, and well adapted to
moist and cold climates on account of the sloping roof. Clustered columns,
the spire or belfry, the arched roof, and the division of the interior into
nave, transept, and choir, are leading features. Natural as well as
conventional treatment of plants is another important characteristic.

[Illustration]

The Gothic style flourished principally in England, France, and parts of
Germany. Nearly all the principal cathedrals and churches in these
countries, and many in our own, are built after this style. The most
beautiful example in this country is St. Patrick's Cathedral, in New York.
The finest specimen in the world is probably the Cathedral of Cologne,
which was commenced in the 14th century, but was not completed until many
years later.


III. MODERN ART.

In the 15th century a remarkable revival occurred in literature and the
fine arts, showing a decided tendency to return to the old classic ideas of
the Greeks and Romans. After an almost complete neglect, which lasted for
centuries, artists and men of letters turned their attention to the long
neglected relics of pagan civilization as worthy of study for their
intrinsic beauty alone. Symbolism was relegated to a minor position, and
beauty was once more cultivated for its own sake. This epoch is termed the
Renaissance--which literally means a rebirth or revival.

1. _Renaissance Style._--The term Renaissance is also applied to one of the
early styles which came into vogue at this time. It flourished principally
in southern Europe. It is not a pure style, but marks a transition period
from the old popular Gothic and Saracenic forms to the revivified classic.
It naturally exhibits a queer mixture of conflicting elements--classic and
mediæval thrown together without much regard to propriety or fitness. It
still showed traces of symbolism.

2. _The Cinquecento Style._--The Renaissance reached its most perfect
development in the Cinquecento or the 15th century style. It followed the
Quatrocento or 14th century style. Entirely untrammeled by symbolism, and
with the whole field of classic and mediæval ornament to glean from, its
aim was to develop a perfect style of ornament. The best examples of this
period are founded on the soundest principles of ornamental art. Nothing
that could be turned into an element of beauty was neglected. Animals, real
and fictitious, flowers, leaves, fruit, the human form, etc., were
conventionalized and made to contribute their part to enhance the beauty of
the whole. Some of the principal characteristics of the Cinquecento style
are the delicate arabesque scroll work, the profusion and beauty of the
curves, its admirable variations of standard classic ornaments, such as the
anthemion and scroll. The coloring, also, was one of its most pleasing
features. This style flourished principally in Italy and France. Farnese
Palace and the tombs of the Medicis are noted examples.

3. _The Louis Quatorze._--This style succeeded the Cinquecento, but was
far inferior to it. It arose in Italy, and while preserving generally the
materials of the style that preceded it, it added as characteristic
features the scroll and the shell. Its principal object was to create
brilliant and startling effects in light and shade. Color was, in
consequence, decidedly secondary, gilding being used everywhere. The Palace
of Versailles, near Paris, is a gorgeous example of this style. Everything
in it is glittering and sparkling. Mirrors are everywhere placed to
intensify this effect. This style was followed by the Louis Quinze,
inferior to it in every respect, and in which symmetry, at least in detail,
seems to be carefully avoided. It still further degenerated into the
Rococo, the most extravagant and exaggerated of all the historic styles,
and which prevailed in the latter part of the 18th and the beginning of the
19th century.

The present century cannot boast of any great characteristic style in
either architecture or ornament. Whether it is only in a course of
development, and what will be the results, time only can show. All styles
are now in vogue, hence the importance of accurate knowledge on the
subject. To be able to judge of and appreciate the best, and to profit by
the labors of those gone before us, at the same time imparting
individuality and character to our own design, should be the aim and object
of the study of decoration, and it should enter into any scheme of general
education and culture.--_Journal of Education_.

       *       *       *       *       *




THE MONTAUD ACCUMULATOR.


This accumulator is of the Plante type, and is modified so as to obtain a
more rapid formation, a larger surface, and a symmetrical distance of the
plates from each other. If into an alkaline bath saturated with litharge
(added in excess) we plunge two lead electrodes and pass in a current of
suitable tension and intensity, there is deposited upon the anode a layer
of peroxide of lead varying in thickness with the intensity of the current,
and more or less rich in oxygen according to the intensity of the bath,
while the cathode is covered with a stratum of reduced lead. The liquid of
the bath supplies material for both deposits, while in galvanoplastic
operations the anode supplies it to the cathode. The principle of the
formation consists in introducing in an efficacious manner currents of a
great intensity, and thus abridging its duration.

Of two plates thus treated, the one becomes positive, and is covered with a
thick layer of peroxide of lead. On leaving the bath it undergoes various
preparations and several washings, and is then fit to be mounted along with
others to form an accumulator ready to be charged and to work. The second,
or negative, plate is covered with a thick sponge of lead. It is carefully
washed, preserved in water with exclusion of air, and submitted to a very
considerable pressure. After this operation it presents the appearance of
ordinary sheet lead, but though the physical porosity has disappeared, the
chemical porosity is intact, and this alone comes into play in
accumulators. When a negative plate is constructed in this manner, it is
ready to be combined with the positives to form an accumulator.

The inventor has sometimes put into the bath at the positive pole negative
plates prepared as just described. They become very easily peroxidized, but
they have the grave defect of requiring two preparations in place of one.
To secure an accumulator against any leakage from plate, the solderings and
the entire plates must be submerged in the liquid, so that nothing projects
up out of the acidulated water except two strong rods for making contact.
These rods are covered with an insulating varnish from their origin to
above the point where they issue from the liquid. The plates are of a
rectangular form (Fig. 1). They are sloped out at one corner, and as two
plates in juxtaposition are cut together, when they are separated the
sloping out of the one serves for the handle of the other. This handle is
doubled back on the plate which is suspended in the bath, so that the part
which has to be soldered does not undergo any preparation. A hole pierced
in this corner of the plate serves to receive a square rod of lead, which
connects the plates together and supports one of the poles or contacts of
the accumulator. At the point of soldering the doubled-down handle gives a
double thickness, and the margins of the plate are folded in such a manner
as to insure their solidity.

[Illustration: FIG. 1.]

The sloped out corner affords the free space necessary for the rod of the
opposite pole, and one and the same plate may be indifferently connected
either to the + or the - at the right or the left. The plates are made of
four different sizes: No. 1, 19 of which serve for an accumulator of 1
square meter; No. 2, 21, 25, or 29 of which serve for accumulators of 2, 3,
and 4 square meters; No. 3, which with 21, 25, or 29 plates composes
accumulators of 5, 6, and 7 square meters; and No. 4, which with 21, 23,
25, 27 or 29 plates forms accumulators of 8, 9, 10, 11, and 12 square
meters.

As the plates are entirely submerged in the liquid their entire surface is
active, and the entire surface being absolutely flat, it is sufficient to
preserve their respective distance at any one point in order to have it
everywhere alike. The weight of the plate depends on the intended duration
of the plate and its capacity. As for the negative plate, its thickness is
the most important factor of its capacity. The proportion has yet to be
established for daily practice. The inventor uses in practice positive
plates of 0.002 meter in thickness. On the other hand, the negative plates
have a body of only 0.001 meter in thickness, their greater thickness being
due only to the deposit of compressed lead. The rod which fixes the plate
to each pole (Fig. 2) is formed of a special alloy of lead and antimony,
not attacked by acid. This gives rigidity to the rod, and hinders it from
binding when the accumulator is taken out of its case. The copper piece
which surmounts it is fitted at its base with an iron cramp, which is fixed
in the lead, and above which is a wide furrow with two grooved parts, which
being immersed in the lead hinders the copper from slipping round under the
action of the screw. The rod is square, and is cast in a single piece.
Against one of its surfaces the ends of the connected plates press flatly
up. A square form has been selected to give more surface for soldering. The
soldering is autogenous (as in the lead chambers at vitriol works). The
soldering, as well as the entire plates, is entirely immersed in the
liquid, and to prevent any leakage an insulating varnish, perfectly proof
against the acid and the current, is laid over the rod from the part
soldered upward.

[Illustration: FIG. 2.]

If it is wished to lift the accumulator from its chest for any
verification, hooks passing between the plates seize hold of the rods, and
thanks to the rigidity of the antimony lead, they effect the removal of the
apparatus without bending the rods in the least. All the parts of the
plates must be kept at exactly the same reciprocal distances, and a
difference of only 0.001 meter between two points is sufficient to affect
the yield considerably. For an insulating material, wood, when plunged in
dilute acid, is preferred by the inventor. He makes a comb of wood, the
teeth of which vary according to the thickness of the plates to be lodged
between them. Fig. 3 represents a comb having 15/10 of a millimeter for the
negative plates and 25/10 for the positive plates.

[Illustration: FIG. 3.]

This appliance, which is 0.01 meter in thickness and 0.02 meter in width in
the back, is made very cheaply by machinery. The weight of the accumulator
bears entirely upon the back of the combs, which are all placed back
downward, and the number of which varies according to the size of the
plates. Small combs of wood clasp the plates at their extremities, and make
the entire accumulator quite compact and manageable. The entire accumulator
is shut up in a wooden chest, which the outer teeth of the comb serve to
insulate from the leaden chest, and to prevent any loss of electricity
along the sides.

Fig. 4 shows the arrangement of the side combs. A single glance at this
figure shows that it would be difficult to have more surface without having
recourse to curved, undulated, or folded plates, in which the distances are
variable, and consequently defective. In the Montaud accumulator, the
weight is simply proportional to the intended duration. For the notion, "So
much capacity and so much yield per kilo.," Montaud substitutes the notion,
"So much capacity or yield per square meter, the weight not being taken
into consideration." These Montaud accumulators are classified as follows:
They have from 1 to 12 square meters of surface, and the number
corresponding to the surface indicates its weight of useful lead, its
manner of charging, its capacity, and its manner of discharge.

[Illustration: FIG. 4.]

According to the inventor's experiments, the square meter of active surface
can receive a charging current of 10 amperes, and furnish on discharging a
current of the intensity of 20 amperes. For a "No. 10" accumulator we have
an active surface of 10 square meters, a charging current of 100 amperes,
and on discharging a current of 200 amperes. A square meter of lead of the
thickness of 0.001 meter weighs about 11 kilos.

As both surfaces of the lead are utilized, their weight is reduced to 5½
kilos. A No. 10 therefore requires 55 kilos. of useful lead. It will be
seen that to increase the thickness of the sheet of lead merely augments
the duration of the accumulator, without affecting its capacity or its
manner of charging and discharging. Nos. 1, 2, 3, and 4 may be placed in
vessels of stoneware, glass, or ebonite, or in boxes of pitch pine, painted
with three coats of gum lac and lined with sheet lead. Nos. 5 to 12 are
only sent out in pitch pine boxes lined with lead. The box is supported on
feet of porcelain of the shape of a mushroom. If a drop of water falls upon
this foot, it cannot give a communication with the earth, since, falling
upon the broad part of the mushroom, it will glide off without running
along the foot, which serves as the stalk of the mushroom. A slip of glass
is placed under each foot; the part which supports the mushroom is covered
with an insulating varnish, which prevents the formation of climbing salts
and preserves the screws from rust. A common layer of insulating varnish is
applied under the head of the mushroom.

As regards the advantages of the Montaud accumulator we notice, first, its
longevity. Dr. D'Arsonval points out that the accumulators of the Plante
class have a great advantage over the Faure type as regards duration, and
that the most striking quality of the Montaud accumulator is its longevity.
The inventor has in his possession positive plates, five to six years old,
completely peroxidized, though there remains in the interior a thin core of
metallic lead sufficient to give passage to the current. The adhesion of
the peroxide is such that to detach it, it must be beaten with a hammer
upon an anvil. The next four points--i.e., the rapidity of charge; the
yield, much greater than that of any other system in proportion to its
surface; its small weight in comparison with its yield; and its capacity,
which for an equal weight is greater than that of any other accumulator. In
his experiments in September, 1885, Dr. D'Arsonval obtained with an
accumulator of 2 square meters of surface:

    Useful capacity        40 ampere hours.
    Total                  62   "      "
    Surface                 2 square meters
    Charge                 10 amp. per sq. meter.
    Discharge              20  "    "        "
    Useful weight of lead  10 kilos.

Representing a total capacity of six ampere hours per kilo., and of a
discharge of 5 amperes per kilo., or a total capacity of 81 ampere hours
per square meter, and a useful capacity of 20 ampere hours per square
meter. Subsequently the modification of the negative plate has greatly
improved these figures, which will certainly become much more advantageous
in future. The total capacity of an accumulator having exactly 1¾ meters of
surface has become 87 ampere hours, which if referred to an accumulator of
2 square meters of surface, would give the following results:

    Useful weight of lead per sq. meter           5½   kilos.
    Total capacity of useful lead per kilo        9.1  amp. hr.
    Total capacity per sq. meter                 50      "
    Useful capacity of per kilo of useful lead    6.23   "
    Useful capacity per square meter             34.30   "
    Current of charge per square meter           10    amp.
    Current of charge per kilo, of useful lead    2     "
    Current of discharge per sq. meter           20     "
    Current of discharge per kilo, of useful lead 4.56  "

The next advantage of the Montaud accumulator is the ease with which it can
be taken out of its box and repaired without special tools and experience.
A capital defect in this respect has hitherto much interfered with the use
of accumulators. In case of accidents, several kinds of which are possible,
it is found very difficult to rectify the apparatus. The Montaud
accumulator is much less liable to accidents, on account of the firmness
and compactness of its construction, and if any accident happens, the
repairs are simple and easy. Lastly, the stout framework secures the
apparatus from any accident due to a disproportionate charge or discharge.
The peculiarities of the combs and rods already described solve this
problem. On September 8, 1885, Dr. D'Arsonval, professor at the College of
France, wrote as follows: "The Montaud accumulator is of the Plante type,
and is extremely well conceived from a mechanical point of view. The
wooden combs prevent the plates from coming in mutual contact, and give the
apparatus great solidity. The process of formation is ingenious and rapid.
To give 1 square meter a capacity of 20 ampere hours, there is required
only a quarter of an hour's treatment.

"To obtain the same result by Plante's method, months are required. The
entire experiments have been effected with No. 2, which has a surface of
two square meters. This apparatus, if charged to saturation, gives 62
ampere hours as its total capacity, and, as in the Plante, this capacity
constantly increases with use. The normal rule for the charge is 10 amperes
per square meter, and for the discharge double this quantity. This
apparatus has always given me on discharging 40 amperes at the E.M.F. of
1.85 volts during 60 or 65 minutes. The charge is effected in two hours up
to 20 amperes, without any appreciable loss of electricity.

"The points to be aimed at in an accumulator are longevity and energy, or,
rather, rapid yield per kilo. From both points of view accumulators of the
Plante type (and consequently those of Montaud) are far superior to those
of the Faure type. My opinion, therefore, is that the Montaud accumulator
is very practical, that it is a great improvement on the Plante type, and
that it can compete successfully with the other systems in use."--_Revue
Internationale de l'Electricite._

       *       *       *       *       *




ELECTRIC REGISTERING APPARATUS FOR METEOROLOGICAL INSTRUMENTS.


Mr. E. Gime, whose name is not unknown to our readers, sends us a
description of a certain number of meteorological apparatus to which he has
applied a peculiar method of registering that it is of interest to make
known.

[Illustration: FIG. 1.--DIAGRAM OF GIME'S TELEMAREOGRAPH.]

Mr. Gime in the first place has devised a "telemareograph," that is to say,
an apparatus designed to register at a distance the curve of the motions of
the tide in a given place. The structure of this device, shown
diagramatically in Fig. 1, is very simple. It is divided into two distinct
parts--a transmitter and a registering apparatus. The transmitter consists
of a long glass tube, A, closed at one end and communicating through the
other with a receptacle filled with mercury. A barometric vacuum is formed
in this tube. The level of the open receptacle corresponds exactly to the
level of the lowest tide.

[Illustration: FIG. 2.--THE APPARATUS WITH THREE REGISTERING STATIONS.]

Pieces of iron wire projecting sufficiently in the interior to establish
good contacts with the column of mercury are fastened one millimeter apart
to the inner surface of the tube. These iron contacts are connected with
the divisions of a rheostat, R, arranged in a tight compartment surrounded
with paraffine, near the tube.

This rheostat is interposed in the general circuit. It is connected through
one extremity with the line, and through the other with a disk of copper,
which has a surface of one square meter, and is immersed in the sea.

The line, L, insulated like an ordinary telegraph wire, is prolonged as far
as to the registering station.

The registering apparatus consists of a solenoid, S, that acts upon a soft
iron core suspended by a cord from the extremity, _x_, of the beam of a
balance. This cord passes between the channels of two rollers designed,
despite the motion of the beam, to keep the core in a vertical position in
the center of the solenoid.

The opposite arm of the balance carries a sliding weight, _i_, that moves
over a graduated scale and is designed to balance the core, N, in a certain
position in regulating the motions of the curve. At its extremity it
carries a style that bears against the drum, T, on which the paper is wound
that is to receive the mareometric curve.

The solenoid, S, is interposed in the general circuit, being connected on
the one hand with the line, L, and on the other with a very constant
battery of an electromotive force proportioned to the resistance of the
circuit.

Through the electrode that remains free, the battery is grounded with so
great care that no variation in resistance can be produced thereby. If the
station is near the sea, the conductor of this electrode may be run to a
copper disk, having the same surface as the one at the transmitting
station. With this description, the operation of the apparatus may be
easily understood.

At low water, the pressure of the atmosphere balances a column of mercury
rising in a glass tube to a height proportionate to such pressure. In
measure as the level of the water rises, the pressure on the mercury in the
receptacle increases, and causes the metal to rise in the tube. The higher
the level of the sea, the less becomes the sum of the resistances of the
rheostat, since the column of mercury puts in short circuit all the
divisions of the rheostat, whose contacts are comprised in the height of
the column.

From these variations in the resistance of the circuit naturally result
variations in the current from the battery, B, at the registering station.
To the variations in intensity of the current in the circuit there
correspond variations in the attraction of the solenoid for the core that
transmits these motions to the balance that carries the registering style,
which latter amplifies or reduces them.

The same transmitter suffices for various registering stations arranged in
series, as shown in Fig. 2.

The variations in the resistance of the circuit, due to variations in the
temperature, and the variations in the height of the column of mercury, due
to atmospheric variations, etc., are, according to the inventor, of no
importance.

It would evidently be possible, on the same principle, to construct an
apparatus for registering the indications of a thermometer at a distance.

Such is the principle of Mr. Gime's apparatus. We do not believe that they
are entirely closed to criticism. What, in fact, are the conditions
essential for their proper working? Evidently: (1) the constancy of the
battery used; (2) a rigorously accurate adjustment. This latter condition,
is easily realized; but the same is not the case with the former. Of what
elements shall this constant battery be formed?

Mr. Gime recommends the use of the Latimer-Clark elements. Every one knows
that the Latimer-Clark element is now the best standard of electromotive
force; but let us not forget that this is on condition of its being
employed in open circuit. Now, it is not a question here of an open
circuit, nor even of infinitely weak currents, since in the line we have a
solenoid whose core must set in motion a whole system of connected pieces.
We do not see any possibility of employing Latimer-Clark elements; on the
contrary, it seems to us indispensable to select piles of large discharge,
since the solenoid, S, will attract nothing at all unless a notable
quantity of energy is expended in it.

Is there a pile of this kind so constant as not to render a rigorously
accurate adjustment illusory? Therein lies the entire question, and for our
part we hesitate to pronounce ourselves in the negative.--_La Lumiere
Electrique._

       *       *       *       *       *




A CLINICAL LESSON AT "LA SALPETRIERE."


[Illustration: THE SALON OF 1887.--A LECTURE IN THE DISPENSARY AT LA
SALPETRIERE.--Painted by M. Andre Brouillet.--M. Dochy. Engraver.]

[Illustration: A CLINICAL LECTURE AT "LA SALPETRIERE."]

We reproduce the picture of Mr. Andre Brouillet, which was in the Salon of
1887; and that the subject may be better understood, we give the
accompanying sketch and description. This picture is very interesting, not
only from an artistic point of view, but also as a representation of
students and spectators of all ages admirably grouped around a great master
of science when most interested in his work. We borrow from _Matin-Salon_
Mr. Goetschy's explanation of the picture:

"The hall in which the lesson is given is lighted by two large windows
opening on one of the courts of the hospital. The Professor stands at the
right of the picture, his head uncovered, one hand close to his body and
the other extended slightly in a gesture which is familiar to him, his
audience being before him. At his side is Mr. Babinski, chief of the
clinic, supporting a person afflicted with hysteria. Near the latter stands
a nurse and assistant who watches every movement of the patient. This is
Mother Bottard, a good, intelligent, and devoted woman, who is well known
to all those present.

"The auditors have arranged themselves at the students' tables, some seated
on the chairs and stools which furnish the room, and others standing, but
all following closely the teaching of the master, and at the same time
watching the _subject_. The picture is full of life and motion, and yet is
very exact. The head and shoulders of the subject are beautifully and
correctly drawn. The artist has brought together many men who are well
known in literature and science."--_Le Monde Illustre_.

       *       *       *       *       *

[NATURE.]




TO FIND THE DAY OF THE WEEK FOR ANY GIVEN DATE.


Having hit upon the following method of mentally computing the day of the
week for any given date, I send it you in the hope that it may interest
some of your readers. I am not a rapid computer myself, and as I find my
average time for doing any such question is about 20 seconds, I have little
doubt that a rapid computer would not need 15.

Take the given date in 4 portions, viz., the number of centuries, the
number of years over, the month, the day of the month.

Compute the following 4 items, adding each, when found, to the total of the
previous items. When an item or total exceeds 7, divide by 7, and keep the
remainder only.

_The Century Item_.--For old style (which ended September 2, 1752) subtract
from 18. For new style (which began September 14) divide by 4, take
overplus from 3, multiply remainder by 2.

_The Year Item_.--Add together the number of dozens, the overplus, and the
number of 4's in the overplus.

_The Month Item_.--If it begins or ends with a vowel, subtract the number
denoting its place in the year from 10. This, plus its number of days,
gives the item for the following month. The item for January is "0;" for
February or March (the 3d month), "3;" for December (the 12th month), "12."

_The Day Item_ is the day of the month.

The total thus reached must be corrected by deducting "1" (first adding 7,
if the total be "0"), if the date be January or February in a leap year;
remembering that every year divisible by 4 is a leap year, excepting only
the century years, in new style, when the number of centuries is _not_ so
divisible (e.g., 1800).

The final result gives the day of the week, "0" meaning Sunday, "1" Monday,
and so on.

EXAMPLES.

1783, _September_ 18.

17 divided by 4 leaves "1" over; 1 from 3 gives "2;" twice 2 is "4."

83 is 6 dozen and 11, giving 17; plus 2 gives 19, i.e. (dividing by 7),
"5." Total 9, i.e., "2."

The item for August is "8 from 10," i.e., "2;" so, for September, it is "2
plus 3," i.e., "5." Total 7, i.e., "0," which goes out.

18 gives "4." Answer, "_Thursday_."

1676, _February_ 23.

16 from 18 gives "2."

76 is 6 dozen and 4, giving 10; plus 1 gives 11, i.e., "4." Total "6."

The item for February is "3." Total 9, i.e., "2."

23 gives "2." Total "4."

Correction for leap year gives "3." Answer, "_Wednesday_."

LEWIS CARROLL.

       *       *       *       *       *




PRECIOUS STONES OF THE UNITED STATES.


To the recently distributed government report on the mineral resources of
the United States for 1885.[1] Mr. G.F. Kunz contributes an interesting
chapter in which is recorded the progress made during that year in the
discovery and utilization of precious stones.

[Footnote 1: Mineral Resources of the United States: Calendar Year 1885.
Washington: Government Printing Office. 1888.]

In the summer of 1885, a remarkably large pocket containing fine crystals
of muscovite, with brilliant crystals of rutile implanted on them, was
found at the Emerald and Hiddenite Mining Company's works, at Stony Point,
N.C., and was sold in the form of cabinet specimens for $750. While the
soil overlying the rock was being worked, nine crystals of emerald were
found, all of which were doubly terminated, and measured from 1 inch to
3-1/8 inches in length and 1-2/3 inch in width. One of these crystals is
very perfect as a specimen, being of a fine light green color, and weighing
8¾ ounces. It is held by the company at $1,500, and the nine crystals
together at $3,000. Another of these crystals, doubly terminated, measures
2½ inches by 11/12 of an inch, and is filled with large rhombohedral
cavities, which formerly contained dolomite. The only crystal from this
collection that has been cut into a gem was found in a pocket at a depth of
over 43 feet. In color it is of a pleasing light green, and it weighs
4-22/32 carats. No crystal of a finer color has as yet been found in the
United States, and the gem is held by the company at $200.

During the recent mining, the largest fine crystal of lithia emerald ever
found was also brought to light. It measures 2¾ inches by 3/5 of an inch
by 1/3 of an inch. One end is of a very fine color, and would afford the
largest gem of this mineral yet found, and one which would probably weigh
5½ carats. With this there was a number of superior crystals and some
ounces of common pieces of the same mineral. The company estimates the
value of this entire yield of hiddenite at about $2,500.

There was also found a quantity of quartz filled with white byssolite,
forming very attractive specimens and valued at $250.

A number of beryls of a fine blue color, resembling the Mourne Mountain
specimens, were found near Mount Antero, Chaffee County, Col. One of these
was 4 inches long and 3/8 of an inch across, with cutting material in it.
The other crystals measured from 1 to 1¼ inch in length, and from 1/5 to
1/3 inch in width.

The large beryl mentioned by Mr. Kunz in the Mineral Resources for 1883 and
1884 has afforded the finest aquamarine of American origin known. It is
brilliant as a cut gem, and, with the exception of a few internal hair-like
striæ, is absolutely perfect. It weighs 133¾ carats, measures 1-2/5 × 1-2/5
× 4/5 inch, and is of a deep bluish green, equal to that of gems from any
known locality.

Mr. G.F. Breed, manager of the Valencia Mica Company, has cut nearly one
hundred aquamarines, ranging from ½ carat to 4 carats in weight, and of a
light blue color, from white beryls found in the company's mica mine at
North Grafton, N.H.

A number of fine, deep golden-yellow, blue, and green beryls, equaling any
ever found, have been taken by Mr. M.W. Barse from his mica mine between
New Milford and Litchfield, Conn. Some fine blood-red garnets from this
same locality have been cut into gems.

The largest phenacite crystal ever found is owned by Mr. Whitman Cross. It
was discovered at Crystal Park, Col., weighs 59 pennyweights 6 grains, and
measures 1-4/5 inch in length and 1-1/5 inch in thickness.

Thousands of garnet crystals, found at Ruby Mountain, near Salides, Col.,
have been made into paperweights and sold to tourists. Those that weigh a
few ounces sell for about ten cents each. One was sold that weighed 14
pounds. Apropos of garnets, the discovery, in the heart of New York city,
of as fine a crystal as was ever found on this continent, and weighing 9
pounds 10 ounces, may be mentioned as a matter of peculiar interest.

Several thousand dollars' worth of the wood jasper of Arizona has been cut
into paper weights, charms, and other objects, or polished on one side for
cabinet specimens. Numbers of these articles are now being cut and sold to
tourists along the line of the Atchison, Topeka, and Santa Fe Railroad.

The compact quartzite of Sioux Falls, Dakota, is being quarried and
polished for ornamental purposes. It is known and sold as "Sioux Falls
jasper," and is really the stone referred to by Longfellow in his Hiawatha
as being used for arrow heads. This stone takes a very high polish, and is
found in a variety of pleasing tints, such as chocolate, brownish-red,
brick-red, and yellowish. For the two years previous to 1885, $15,000 worth
of it was sold.

A remarkable mass of rock crystal has been received by Messrs. Tiffany &
Co. from a locality near Cave City, Va. Although this mass weighs 51
pounds, it is but a fragment of the original crystal, which weighed 300
pounds, and which was broken in pieces by the ignorant mountain girl who
found it. The fragment, as it is, will furnish slabs 8 inches square and
from 1/3 to 1 inch thick. The original crystal would have furnished a ball
from 4½ to 5 inches in diameter, and almost perfect. A number of fine
agates of various kinds were found by Mr. F.C. Yeomans at the same
locality.

The meccanite from Cumberland, R.I., is often spotted with white quartz. It
has been cut into oval stones several inches in length, which take a fine
polish. This quality, coupled with its hardness, makes it a desirable
ornamental gem stone.

Mr. Kunz records the discovery, by himself, in the largest mass of the
Glorieta Mountain (Santa Fe County, N.M.), of pieces of peridot of
sufficient transparency to afford gems one-fifth of an inch in length.

Large quantities of turquoise from Los Cevillos, N.M., have been sold, both
as cabinet specimens and gems; but, unfortunately, many of those of the
finest color have been found to be artificially colored.

Malachite in large masses has been found at the Copper Queen mine at
Bisbee, Oregon. One of these masses weighed 15 pounds and others were quite
as large. All were of good enough quality and large enough for table tops.

In conclusion, Mr. Kunz says that "the National Museum collection of gems,
formed by Prof. F.W. Clarke, is now one of the most complete, for species,
in the United States, and as many of the gems are of more than average
merit, and all can have access to them, this is one of the best
opportunities afforded the student in this country."

       *       *       *       *       *




THE BRAZIL NUT.


[Illustration: THE BRAZIL NUT.]

Every one is acquainted with the hard-shelled, triangular fruit called the
Brazil nut, but there are, perhaps, but few who know anything about the
tree that produces it, or its mode of growth. The Brazil nut tree belongs
to a genus of Lecythidaceæ of which there is only one species,
_Bertholletia excelsa_. This tree is a native of Guiana, Venezuela, and
Brazil. It forms large forests on the banks of the Amazons and Rio Negro,
and likewise about Esmeraldas, on the Orinoco, where the natives call it
_juvia_. The natives of Brazil call the fruit _capucaya_, while to the
Portuguese it is known as _castaña de marañon_.

The tree is one of the most majestic in the South American forests,
attaining a height of 100 or 150 feet. Its trunk is straight and
cylindrical, and measures about 3 or 4 feet in diameter. The bark is
grayish and very even. At a distance, the tree somewhat resembles a
chestnut. Its branches are alternate, open, very long, and droop toward the
earth. The leaves are alternate, oblong, short petioled, nearly coriaceous,
about 2 feet long by 6 inches wide, entire or undivided, and of a bright
green color. The flowers have a two-parted, deciduous calyx, six unequal
cream-colored petals, and numerous stamens united into a broad, hood-shaped
mass, those at the base being fertile, and the upper ones sterile.

The fruit is nearly orbicular, and about 6 inches in diameter, and has a
hard shell about half an inch thick, which contains from 18 to 24
triangular, wrinkled seeds that are so beautifully packed within the shell
that when once disturbed it is impossible to replace them. When these
fruits are ripe, they fall from the tree and are collected into heaps by
troops of Indians called _Castanhieros_, who visit the forests at the
proper season of the year expressly for this purpose. They are then split
open with an ax, and the seeds (the Brazil nuts of commerce) taken out and
packed in baskets for transportation to Para in the native canoes. The
"meat" that the Brazil nut contains consists of a white substance of the
same nature as that of the common almond, and which is good to eat when
fresh, but which, by reason of its very oily nature, soon gets rancid.
Besides its use as an article of dessert, a bland oil, used by watchmakers
and artists, is obtained from the nut by pressure. Brazil nuts form a
considerable article of export from the port of Para, whence they are
sometimes called Para nuts.

The Brazil nut tree remained for a long time unknown to European botanists,
although the fruit has been from a very remote epoch consumed in large
quantities in certain southern countries of the New World. The first
description of the tree we owe to Humboldt and Bonpland, who established
the genus and species in the botanical part of the account of their voyage.
The genus is dedicated to the illustrious Berthollet.

"We were very fortunate," say these authors, "to find some of these nuts in
our travels on the Orinoco. For three months we had been living on nothing
but poor chocolate and rice cooked in water, always without butter, and
often without salt, when we procured a large quantity of the fresh fruits
of the _Bertholletia_. It was along in June, and the natives had just
gathered them."

The formation of a large woody fruit, often in the shape of an urn, from
which the top spontaneously separates in the form of a lid, is one of the
characteristics of the order Lecythidaceæ, which includes the _Couronpita
Guianensis_, or "cannon ball tree"; the gigantic _Lecythis ollaria_, or
"monkey-pot tree," whose great woody pericarps serve as drinking vessels;
and the _Lecythis Zabucajo_, whose fruit is known in the market as sapucaia
nuts, and is greatly superior to the closely allied Brazil nuts as regards
flavor and ease of digestion.

All the trees of this order are natives of South America, and especially of
Guiana.

       *       *       *       *       *




THE ACTION OF THE MAGNET IN HYPNOSIS.


Mr. Tamburini some time ago observed that, during a period of lethargy, the
approach of a magnet produced in persons affected with hysterical hypnosis
a series of modifications of the respiratory functions and of
contractility.

From some very careful experiments made by him and Mr. Righi in common,
upon the lady who was the principal subject of his observations, it results
that (1) it makes no difference whether the magnet be presented by its
poles or its neutral line; (2) that any mass of metal whatever acts like a
magnet; (3) that an electromagnet produces exactly the same effect whether
it be or be not excited by a current; and (4) that a glass tube filled with
cold or warm water likewise produces analogous effects, which disappear
when the water is raised to the temperature of the human body.

It seems, therefore, that the magnetic properties of the magnet count for
nothing in the phenomena observed.--_Journal de Physique_.

       *       *       *       *       *




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