The Project Gutenberg EBook of Scientific  American, Volume XXIV., No. 12,
 March 18, 1871, by Various

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Title: Scientific  American, Volume XXIV., No. 12,  March 18, 1871
       A Weekly Journal of Practical Information, Art, Science,
       Mechanics, Chemistry, and Manufactures.

Author: Various

Release Date: September 5, 2006 [EBook #19180]

Language: English

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[Illustration]




SCIENTIFIC AMERICAN




A WEEKLY JOURNAL OF PRACTICAL INFORMATION, ART, SCIENCE, MECHANICS,
CHEMISTRY, AND MANUFACTURES.


NEW YORK, MARCH 18, 1871.

Vol. XXIV.--No. 12. [NEW SERIES.]

$3 per Annum [IN ADVANCE.]

       *       *       *       *       *




SCIENTIFIC AMERICAN.

MUNN & CO., Editors and Proprietors.

PUBLISHED WEEKLY AT

NO. 37 PARK ROW (PARK BUILDING), NEW YORK.

O. D. MUNN.            S. H. WALES.            A. E. BEACH.

VOL. XXIV., NO. 12 ... [NEW SERIES.] _Twenty-sixth Year_

NEW YORK, SATURDAY, MARCH 18, 1871.

       *       *       *       *       *




CONTENTS:


(Illustrated articles are marked with an asterisk.)

  *Knots and Splices                                     175
  Influence of Cold on Iron and Steel.                   176
  Oak Graining in Oil Colors                             176
  Knots and Splices (Explanation)                        177
  Hartford Steam Boiler and Insurance Co.'s Report       177
  *Improved Spiral Spring for Railway Carriages          178
  *Portable Writing and Copying Case                     178
  How Walking-sticks are Made                            178
  Flowering of the Victoria Regia                        178
  Jute                                                   178
  Ventilation of the Liverpool Tunnel                    178
  *Impregnating Wood with Tar, etc.                      178
  *Boardman's Combined Tool                              179
  *Belt Tightener                                        179
  Some Things I don't want in the Building Trades        179
  *Action of the Reciprocating Parts of Steam Engines    179
  *Answer to Practical Problem                           179
  Reciprocating Parts of Steam Engines                   179
  Test for White Lead                                    180
  How to Build a Chimney                                 180
  Crystallized Honey                                     180
  Rambles for Relics.--No. 2                             180
  Silk Culture                                           181
  *Universal Boring Machine                              182
  *Combined Trunk and Rocking-chair                      182
  Cosmetics                                              182
  *Smith's Infant Dining-chair                           182
  The Medicines of the Ancients                          182
  *Barnes Ventilator for Mattresses                      182
  Exhibition of the National Photographic Association    182
  A Scientific and Technical Awakening                   183
  The Sherman Process                                    183
  Rubber Tires for Traction Engines                      183
  Central Shaft of the Hoosac Tunnel                     184
  A Museum of Art and Natural History                    184
  Report of Judges, American Institute Fair.
                    --The Allen Engine                   184
  Lyceum of Natural History                              184
  Warming and Ventilating Railroad Cars                  184
  The Mineral Resources of Missouri                      185
  Scientific Intelligence                                185
  American Institute of Mining Engineers                 185
  Consumption of Sugar, Coffee, and Tea                  185
  Unpleasant Discovery in the Patent Office              185
  Substitute for Albumen in Photography (omitted)        185
  Louisiana State Fair                                   185
  Test for Purity of Water                               185
  New Books and Publications                             185
  Business and Personal                                  186
  Answers to Correspondents                              186
  Applications for the Extension of Patents              186
  Recent American and Foreign Patents                    187
  Queries                                                187
  Inventions Patented in England by Americans            187
  List of Patents                                        187

       *       *       *       *       *




THE INFLUENCE OF INTENSE COLD ON STEEL AND IRON.

[Condensed from Nature.]


There has recently been a most interesting discussion at the Literary
and Philosophical Society, Manchester, on the above subject.

The paper which gave rise to the discussion was by Mr. Brockbank, who
detailed many experiments, and ended by stating his opinion that iron
does become much weaker, both in its cast and wrought states, under
the influence of low temperature; but Mr. Brockbank's paper was
immediately followed by others by Sir W. Fairbairn, Dr. Joule, and Mr.
Spence, which at once put an entirely new complexion on the matter.

Dr. Joule says:

"As is usual in a severe frost, we have recently heard of many severe
accidents consequent upon the fracture of the tires of the wheels of
railway carriages. The common-sense explanation of these accidents is,
that the ground being harder than usual, the metal with which it
is brought into contact is more severely tried than in ordinary
circumstances. In order apparently to excuse certain railway
companies, a pretence has been set up that iron and steel become
brittle at a low temperature. This pretence, although put forth in
defiance, not only of all we know, of the properties of materials, but
also of the experience of everyday life, has yet obtained the credence
of so many people that I thought it would be useful to make the
following simple experiments:

"1st. A freezing mixture of salt and snow was placed on a table. Wires
of steel and of iron were stretched, so that a part of them was in
contact with the freezing mixture and another part out of it. In every
case I tried the wire broke outside of the mixture, showing that it
was weaker at 50° F., than at about 12° F.

"2d. I took twelve darning needles of good quality, 3 in. long, 1/24
in. thick. The ends of these were placed against steel props, 2-1/8
in. asunder. In making an experiment, a wire was fastened to
the middle of a needle, the other end being attached to a spring
weighing-machine. This was then pulled until the needle gave way. Six
of the needles, taken at random, were tried at a temperature of 55°
F., and the remaining six in a freezing mixture which brought down
their temperature to 12° F. The results were as follow:--

        Warm Needles.          Cold Needles.
         64 ounces broke        55 ounces broke
         65   "      "          64   "      "
         55   "      "          72   "      "
         62   "      "          60   "    bent
         44   "      "          68   "    broke
         60   "    bent         40   "      "
         ---                    ---
Average, 58-1/3        Average, 59-5/6

"I did not notice any perceptible difference in the perfection of
elasticity in the two sets of needles. The result, as far as it goes,
is in favor of the cold metal.

"3d. The above are doubtless decisive of the question at issue. But
as it might be alleged that the violence to which a railway wheel is
subjected is more akin to a blow than a steady pull; and as, moreover,
the pretended brittleness is attributed more to cast iron than any
other description of the metal, I have made yet another kind of
experiment. I got a quantity of cast iron garden nails, an inch and
a quarter long and 1/8 in. thick in the middle. These I weighed,
and selected such as were nearly of the same weight. I then arranged
matters so that by removing a prop I could cause the blunt edge of a
steel chisel weighted to 4lb. 2oz., to fall from a given height upon
the middle of the nail as it was supported from each end, 1-1/16 in.
asunder. In order to secure the absolute fairness of the trials, the
nails were taken at random, and an experiment with a cold nail was
always alternated with one at the ordinary temperature. The nails to
be cooled were placed in a mixture of salt and snow, from which they
were removed and struck with the hammer in less than 5"."

The collective result of the experiments, the details of which need
not be given, was that 21 cold nails broke and 20 warm ones.

Dr. Joule adds, "The experiments of Lavoisier and Laplace, of Smeaton,
of Dulong and Petit, and of Troughton, conspire in giving a less
expansion by heat to steel than iron, especially if the former be in
an untempered state; but this, would in certain limits have the effect
of strengthening rather than of weakening an iron wheel with a tire of
steel.

"The general conclusion is this: Frost does _not_ make either iron
(cast or wrought), or steel, brittle.

Mr. Spence, in his experiments, decided on having some lengths of
cast iron made of a uniform thickness of ½ in. square, from the same
metal and the same mould.

He writes:--"Two of the four castings I got seemed to be good ones,
and I got the surface taken off, and made them as regular a thickness
as was practicable.

"I then fixed two knife-edged wedges upon the surface of a plank, at
exactly nine inches distance from each other, with an opening in the
plank in the intervening space, the bar being laid across the wedges,
a knife-edged hook was hung in the middle of the suspended piece of
the bar, and to the hook was hung a large scale on which to place
weights.

"The bar was tried first at a temperature of 60° F.; to find the
breaking weight I placed 56lb. weights one after another on the scale,
and when the ninth was put on the bar snapped. This was the only
unsatisfactory experiment, as 14 or 28lb. might have done it, but I
include it among others. I now adopted another precaution, by placing
the one end of the plank on a fixed point and the other end on to a
screw-jack, by raising which I could, without any vibration, bring the
weight to bear upon the bar. By this means, small weights up to 7lb.
could be put on while hanging, but when these had to be taken off and
a large weight put on, the scale was lowered to the rest, and again
raised after the change was made. I may here state that a curious
circumstance occurred twice, which seems to indicate that mere raising
of the weight, without the slightest apparent vibration, was equal in
effect to an additional weight. 3¾ cwts. were on the scale, a 14lb.
weight was added, then 7lb., then 4lb., 2lb., 1lb., and 1lb., making
4cwts. and 1lb. This was allowed to act for from one to two minutes,
and then lowered to take off the small weights, which were replaced by
a 56lb. with the intention of adding small weights when suspended; the
whole was then raised so imperceptibly by the screw, that the only way
of ascertaining that it was suspended, was by looking under the scale
to see that it was clear of the rest. As soon as it was half-an-inch
clear it snapped, thus breaking at once with one pound less than it
resisted for nearly two minutes.

"Six experiments were carefully conducted at 60° F., the parts of the
bars being selected so as to give to each set of experiments similar
portions of both bars; the results are marked on the pieces. My
assistant now prepared a refrigerating mixture which stood at zero,
the bars were immersed for some time in this, and we prepared for the
breaking trials to be made as quickly as could be, consistently with
accuracy; and to secure the low temperature, each bar, on being placed
in the machine, had its surface at top covered with the freezing
mixture. The bars at zero broke with more regularity than at 60°, but
instead of the results confirming the general impression as to cold
rendering iron more brittle, they are calculated to substantiate
an exactly opposite idea, namely, that reduction of temperature,
_cæteris paribus_, increases the strength of cast iron. The only
doubtful experiment of the whole twelve is the first, and as it stands
much the highest, the probability is that it should be lower; yet,
even taking it as it stands, the average of the six experiments at
60° F., gives 4cwt. 4lb. as the breaking weight of the bar at that
temperature, while the average of the six experiments at zero gives
4cwt 20lb. as the breaking weight of the bar at zero, being an
increase of strength, from the reduction of temperature, equal to 3.5
per cent."

Sir W. Fairbairn states: "It has been asserted, in evidence given at
the coroner's inquest, in a recent railway accident, that the breaking
of the steel tire was occasioned by the intensity of the frost, which
is supposed to have rendered the metal, of which this particular
tire was composed, brittle. This is the opinion of most persons, but
judging from my own experience such is not the fact. Some years since
I endeavored to settle this question by a long and careful series
of experiments on wrought iron, from which it was proved that the
resistance to a tensile chain was as great at the temperature of zero
as it was at 60° or upwards, until it attained a scarcely visible red
heat."

The immense number of purposes to which both iron and steel are
applied, and the changes of temperature to which they are exposed,
renders the inquiry not only interesting in a scientific point of
view, but absolutely necessary to a knowledge of their security under
the various influences of those changes. It was for these reasons
that the experiments in question were undertaken, and the summary of
results is sufficiently conclusive to show that changes of temperature
are not always the cause of failure. Sir W. Fairbairn adds: "The
danger arising from broken tires does not, according to my opinion,
arise so much from changes of temperature as from the practice of
heating them to a dull red heat, and shrinking them on to the rim of
the wheels. This, I believe, is the general practice, and the unequal,
and in some cases, the severe strains to which they are subject, has a
direct tendency to break the tires."

       *       *       *       *       *




OAK GRAINING IN OIL COLORS.

CONDENSED FROM THE BUILDING NEWS.


There is a charm and feeling about work executed by the hand, which
gives it a value no mere machine work can possess. Machine work, from
its very nature, necessitates a repetition of pattern, which cannot
be avoided. Hand-work, on the contrary, can imitate every variety, and
follow nature so closely that no two pieces need be alike. There
is also in hand-work a wide scope for the inventive faculty and
the exercise of good taste (both in form and color) and skillful
workmanship. As a rule, strong contrasts between the ground and the
graining color should be avoided. The figure and grain should of
course be seen clearly, but only so clearly as to be distinct, without
interfering with the general and uniform quietness of tone necessary
to fulfil the conditions required by the laws of harmony and good
taste. Violent contrasts and gaudy coloring are always vulgar,
brilliancy and richness of color are not necessarily vulgar; it is
the absence of the guiding power of knowledge and pure taste in their
arrangement which degrades them to the rank of vulgarity. We have
before spoken of the importance of good combing, and of the various
kinds of combs used; we now proceed to describe how the work is done.
The graining color is brushed over the work, in the ordinary manner,
with a pound-brush, care being taken not to put too much color on,
or else it is very liable to be dirty. A dry duster is now used to
stipple with, which, if properly done, will distribute the color
evenly; it is now ready for combing. In the real oak it will be found,
as a rule, that the grain is invariably coarser on one side of the
panel than on the other; this arises from the very nature of the
growth of the tree; it is, therefore, well to imitate this
pattern, and in order to do so we take first a medium or coarse cut
gutta-percha comb, and draw it down one side of the panel; then use a
finer one to complete it. This comb will leave the marks of the grain
in clear unbroken lines from top to bottom of the panel. We now take a
fine steel comb and go over the whole of the previous combing, moving
it in a slanting or diagonal direction across the previous grain, or
with a quick and short wavy motion or curl; both the former and the
latter motion will break up the long lines, left by the gutta-percha
comb, into short bits, which of course represent the pores or grains
of the real wood. There are several other motions of the comb having
the same end in view; and by using the gutta-percha or cork combs, in
conjunction with the fine steel, an infinite variety of grain may be
produced. Steel combs, with one or more folds of thin rag placed
over the ends of the teeth are a style of comb which has nothing to
recommend it. A natural variation in the grain may be produced by one
comb alone, according to the manner in which it is held. For instance,
if we take a coarse or broad-toothed gutta-percha comb, and commence
at the top of a panel, with the comb, placed at its full width: if
drawn down in this position it will leave a grain of the same width
as the width of the teeth: but if we start with the full width, and
gradually turn the comb or slightly incline it to one side--that is to
say, on its edge, we thereby graduate the grain from coarse to fine
at pleasure, and by holding the comb at a certain inclination we may
actually make very fine the coarse comb. A very important point is
the formation of the joints in the wood, as much of the effect of
otherwise good work is lost in consequence of neglect in this respect.
In looking at a real oak door, the joints of the stiles and rails are
clearly and sharply defined, not by any defect of workmanship, but
by the difference in the run of the grain, the stiles being
perpendicular, and the rails horizontal. The rails being cut sharp
off by the stiles, show a perfectly straight line. The light also acts
differently upon the two, simply because the grain or fibre of the
wood is exposed to its influence under different aspects. This also
tends to produce a difference in the depth of the color of rails and
stiles, and panels also. It will be evident that no imitations can be
considered really good except they include these seemingly unimportant
points.

It is a common practice for grainers to imitate a broad piece of heart
or sap of oak, upon the back rail of almost every door they do, and
many of them are not even content with that, but daub the stiles over
from top to bottom with it also. There is nothing so vulgar or in
such bad taste. It should only be done upon those parts of the work on
which it would appear on a real oak door, namely, on the edges of the
doors and on mouldings. There is a vulgar pretentiousness about what
we may call the sappy style of work which is very undesirable. The
figures cross the grain more or less abruptly and of course are of
different shapes, sizes, and forms, a knowledge of which can only be
acquired by study of the real wood. The figure may be wiped out with
a piece of soft rag, held tight over the thumb nail. This should have
two or three folds over the nail, the superfluous rag being held by
the other hand to prevent it hanging down and smearing the grain; and
every time a figure is wiped, the rag should be moved slightly, so
that the same part of the rag will not be used twice, thus insuring
clean work. It will often happen that the thumb-nail will get broken,
or is too weak to stand the work; in these cases, or, in fact, in
any case, a good substitute or artificial thumb-nail may be made of
gutta-percha, thus: A piece of thin sheet gutta-percha is put into
warm water, and, while soft, is wrapped around the end of the thumb up
to the first joint. It is then pressed with the hand, so as to fit
and take the shape of the thumb and nail. This cannot be done at one
heating, but will have to be put into the hot water again, and the end
pinched and squeezed into form to the shape of the nail, and to fit
easily upon the thumb. When this gets hard, it may be trimmed into
perfect form with a penknife. This artificial nail will answer the
purpose admirably if properly made; and even when the natural nail
is good, the gutta-percha will serve to save it from injury. Good
figuring may also be done by using the blank end of the steel
comb with a rag folded over its edge. We have also used a piece of
gutta-percha to take out the lights. This should be square-ended,
about one inch wide, and three or four inches long, and will do
successful work of a certain class, but not of the best. Many grainers
use a piece of thin horn, in shape something like a spatula, about
three or four inches long and three quarters of an inch wide, with
rounded ends, and quite flexible. With this tool the figure is cut
or scooped out--a sort of quick, side-long motion, very difficult to
describe, and requiring a very considerable amount of practice
before it can be worked with any success. There is, however, the same
objection to this tool as may be urged against the gutta-percha for
figuring, namely, that neither of them take the color clean away, but
leave an accumulation of color on the edge of the figure, which is
fatal to good work; and therefore we cannot honestly recommend the
use of any method but the wiping out with the thumb-nail or its
substitute. When the figure is wiped out it will require to be
softened. By softening, we mean the imitation of those half shades
seen upon and about the figures in the real wood. Between and around
the lights or figure in oak, there is always a lighter tint of color;
this is imitated by doubling a piece of rag into a small roll, and
with the side of this the grain is partially wiped away, but not to
the extent of taking off the whole of the grain. A recent but most
admirable system of graining oak, by means of over-combing, is worked
exactly the reverse of any of the foregoing methods; that is to
say, the figure is first wiped out, and the combing or grain is done
afterwards, when the graining color is dry, in this wise: The graining
color is mixed somewhat thinner than for ordinary graining, and is
brushed over the work sparingly, leaving it just sufficiently strong
to show a clear distinction between the ground and the color. The
light or figure is then softened by drawing the end of a flat hog-hair
fitch, or a small thin mottler, across each figure, and slightly
softening with the badger-hair softener. The figure is broken up a
little with fine lines across it in parts, such as may be seen in the
real wood; but previous to wiping out the figure, streaks of light
should be wiped out and softened on one side of the panel or across
the stiles, in imitation of the reflective lights seen in oak. The
color should also be partially wiped off the rails or stiles at their
junction; this tends to define the joint. The color is now let to
dry hard, when it will be ready for over-combing--that is, combing or
graining over the figure (hence its name), and this will have to be
done somewhat differently to the ordinary combing. As thus: The color
is rubbed in as before, and combed solely with the gutta-percha combs,
but these are specially cut for the purpose; they are best about 2 in.
wide. The first must be cut with teeth about three-sixteenths of an
inch in width, the next one-eighth, and the third about one-sixteenth.
The broad-toothed comb is first used, and must be drawn down the
panel, with a wavy motion, in short or long curls; either will
answer our purpose now. The next size of comb is then drawn straight
down--the straighter the better. This has the effect of breaking the
wavy combing into short and long straight bits, similar to the pores
or grain of the real wood. Both the first and second combing may be
varied by holding the comb in a slanting direction, and may be fine or
coarse, according to the width of the combs used; now take a soft rag
folded, and with this partially clear off the grain which runs over
the figure, leaving only a sufficient quantity crossing the light
or figure, to be just distinguished, exactly as it appears upon the
figure in real oak. The grain is also wiped off in parts on the plain
spaces between the figure, in order to break it up and take away any
formality. If this method be well and probably done, a thoroughly
deceptive imitation may be produced; and except this end be kept in
view, no really good work will result.

       *       *       *       *       *




KNOTS AND SPLICES.


[_SEE ENGRAVING ON FIRST PAGE._]

1. Turn used in making up ropes.

2. End tapered for the purpose of passing it readily through a loop.
To make this, we unlay the rope for the necessary length, reducing
a rope diminishing in diameter towards the end, which is finished
by interlacing the ends without cutting them, as it would weaken the
work; it is lastly "whipped" with small twine.

3. Tapered end, covered with interlaced cordage for the purpose of
making it stronger. This is done with very small twine attached at
one end to the small eye, and at the other to the strands of the rope,
thus making a strong "webbing" around the end.

4. Double turn used for making rope.

5. Eye splice. The strands of the cable are brought back over
themselves, and interlaced with their original turns, as in a splice.

6. Tie for the end of a four-strand rope.

7. The same completed; the strands are tied together, forming loops,
laying one over the other.

8. Commencement for making the end by interlacing the strands.

9. Interlacing complete, but not fastened.

10 and 11. Shell in two views used in No. 65, showing the disposition
of it at the throat. This joining is advantageous, as it does not
strain the cords, and it prevents them from cutting each other; so
that the rings pass one into the other and are joined outside the
intermediate shell.

12. Interlacing in two directions.

13. Mode of finishing the end by several turns of the twine continued
over the cable.

14. Interlacing commenced, in one direction.

15. Interlacing finished, the ends being worked under the strands, as
in a splice.

16. Pigtail commenced.

17. Interlacing fastened.

18. Pigtail with the strands taut.

19. Dead eye, shown in two views.

20. Pigtail finished. We pass the ends of the strands, one under the
other, in the same way as if we were making a pudding splice: thus
bringing it in a line with the rope, to which it is seized fast, and
the ends cut off.

21. Scull pigtail; instead of holding the ends by a tie, we interlace
them again, as in No. 16, the one under the other.

22. Pigtail, or "lark's nest." We make this to the "pennant" of a
cable, which has several strands, by taking the requisite number of
turns over the pudding, in such a manner that the strands shall lay
under each other. This "pigtail" forms a knot at the end of the
rope. It thus draws together two ropes, as shown in No. 32, forming a
"shroud" knot. In these two pigtails, the strands are crossed before
finishing the ends, so that the button, a, is made with the strands,
a, and b, with those of the rope, b.

23. Slip clinch to sailors' knot.

24. Slip clinch, secured.

25. Ordinary knot upon a double rope.

26. Bowline knot for a man to sit in at his work.

27. Called a "short splice," as it is not of great length, and
besides, can be made quickly.

30. Long splice. This extends from a to b. We unlay the strands of
each of the ropes we intend to join, for about half the length that
the splice will be, putting each strand of the one between two strands
of the other.

31. Simple fastening on a rope.

32. A "shroud" knot.

33. The ends of the rope are prepared for making the splice (No.
29) in the same manner as for the "shroud" knot in No. 32. When the
strands are untwisted, we put the ends of two cords together as close
as possible, and place the ends of the one between the strands of the
other, above and below alternately, so as to interlace them as in No.
29. This splice is not, however, very strong, and is only used when
there is not time to make a long splice, which is much the best.

34 and 35. Marline spikes. Tools made of wood or iron, used to open
out a rope to pass the strands of another through it.

36. Shows strands arranged as described in No. 30.

37. Fastening when a lever is used, and is employed when hauling upon
large ropes, where the strength of several men are necessary.

38. A "pudding splice." This is commenced, like the others, by placing
the rope end to end, the turns of the one being passed between those
of the other; having first swelled out the yarns by a "rat's-tail," we
put them, two by two, one over the other, twisting them tightly, and
opening a way for them with the marlinspike. The inconvenience of this
splice is, that it is larger in diameter than the rope itself; but
when made sufficiently long, by gradually reducing the size of the
strands, it has great strength.

39. This shows two strands, a and b, of the ropes, A B, knotted
together, being drawn as tight as possible; we unlay the strand,
a', of the rope, A, for half the length of the splice, and twist the
strand, b', of the rope, B, strongly in its place, tying a' and b'
together tightly. The same process is again gone through on the rope,
B, the strand, a", of the rope, A, being knotted to the strand, b",
of the rope, B. When all the strands are thus knotted together, we
interlace them with the strands of the cable. Thus the strands, a a'
a", are interlocked by being passed alternately above and below the
turns of the cord, B, the ends being also sometimes "whipped." In the
same manner the strands, b b' b", pass alternately over and under
the strands of the rope, A, and are in like manner "whipped." It is
important that the several interlacings and knots should not meet at
one point; we reduce the size of the strands towards the end, so that
they loose themselves in the body of the splice, cutting off such
parts as may project. This splice is employed for joining the ends of
a rope when a chafed part has been cut out, and is quite as strong as
the rope itself.

40. Belaying-pin opened to serve as a button; these are used where it
is necessary to stop or check velocity.

41. Chain knot, or fastening.

42. Variable or regulating lashing. By laying the piece, a f,
horizontally, it can be slipped along the rope, b; by raising or
lowering this, we shall raise or depress the weight, c, the cord, b,
running over the two pulleys, d, from the piece, a f, in the direction
shown in the figure. The friction of the cord, b, passing through the
hole, e, sufficiently fixes the piece, a f, and holds the weight, c,
securely.

43. Cleet, with three ties.

44. Cleet, showing the mode of belaying the cord.

45. The piece, a f, of No. 42.

46. Fair leader.

47. Cleet to be fixed to a stay.

48. Loop for slipping other lines.

49. A "bend" which is only used for fear of the stoppers snapping.

50. Bastard loop, made on the end of the rope, and whipped with yarns.

51. Tie to pins: a, the pin; b, small cords fixed by a cross tie.

52. Cleet, fixed to the "rail," either with screws or nails, to which
the lines are belayed.

53. Waterman's knot.

54. Fair leader.

55. Tie, or bend to pier.

56. Simple fastening to tie.

57. Fastening by a loop. This can be tied or untied without loosening
the loop itself. It is made by following, towards the longer loop, the
direction as numbered 1, 2, 3, 4, 5, and is terminated by the loop, 6,
7, 6, finally passing it over the head of the post, A. This knot holds
itself, the turns being in opposite directions. To untie it, we slack
the turns of the cable sufficiently to again pass the loop, 6, 7, 6,
over the post, A, and turn the ends in the contrary direction to that
in which they were made (as 5, 4, 3, 2, 1).

58. Iron "shell," in two views.

59 and 60. "Wedding" knots; a b, eyelets; c d, the join; e, the
fastening.

61. Lark's-head fastening to running knot.

62. A round turn; the cord, a, is passed through the bight of the
cord, b, over the button, c, where it is secured by an ordinary knot.

63. Belaying-pin splice. The cord, b, "stops" the pin, e, its end
being spliced upon itself, and "served" with yarn; this rope, with its
pin, is passed through the spliced eye, f of the line, g.

64. Round button.

65. Joint by a spherical shell, each loop, a and b, being made by ties
and splices, and surrounding the shell, c.

66. Belaying-pin, shown separately, before being stoppered.

67. Fastening to shears.

68. Square mooring. When the cable is round the post, A, and the
piece, c, without being crossed, it lays in the section 1, 2, 3, 4, 5,
6, 7, and the end is fastened by tying.

69. Wooden shell in section.

70. Crossed fastening. The turns of the cable, passing in front of the
post, B, are crossed at the back of C, in the direction 1, 2, 3, 4, 5,
6, 7, 8, the end, 8, being secured to the cable.

71. Wooden shell.

72. Double-chain fastening.

73. Lashing for "ram" block, or "dead-eye." The ram blocks, a and b,
are strapped by the cords, e, which hold them; the small lanyards,
d, pass through the holes to make the connection, and as they are
tightened give the requisite tension to the cordage; the ends are
fastened to the main rope. Usually one of these dead-eyes is held by
an iron strap to the point where it is required to fix and strain the
cordage, which is ordinarily a shroud.

74. Chain fastening.

  1'. Simple band, showing the upper side.

  2'. The same, showing the under side and the knot.

  3'. Tie, with crossed ends, commenced; a turn is taken under the
  strands, to hold the ends of the cord.

  4'. The same, completed.

  5'. Bend with crossed strands, commenced, the one end being looped
  over the other.

  6'. The same, completed.

  7'. Necklace tie, seen on the upper side.

  8'. The same, seen underneath. The greater the strain on the cords,
  the tighter the knot becomes.

  9' and 10' are similar splices to 7' and 8' with slight
  modifications.

  11' shows the commencement of 13', the legs in elevation; 12' being
  a front view. An ordinary band, made by several turns of a small
  rope, is lapped round them and hauled taut, and then interlaced at
  the ends. This done, the legs are shifted into the shape of a St.
  Andrew's cross. Thus the lashing is tightened, and, for further
  security, we pass the line several times over the tie and between
  the spars, knotting the ends.

  13'. Portuguese knot. This is a lashing for shear legs, and must be
  tight enough to prevent the spars slipping on each other; the
  crossing of the two legs gives a means of securing the knot.

  14'. For binding timbers; a, knot commenced. Take several turns
  round the timbers, and fasten the ends by passing them under the
  turns; b, knot completed. The end of a round stick, m n, termed a
  packing stick, should be passed under the knob, the cord being slack
  enough to allow of this. By turning the stick, the turns can be
  tightened to any extent; when tight, we fasten the longer arm of the
  lever to some fixed point, by a rope, p q, so that it cannot fly
  back. Care must be taken not to turn the stick too far, or the rope
  may be broken. As the timber dries and shrinks, the lever may be
  used to make all taut again.

       *       *       *       *       *




THE HARTFORD STEAM BOILER INSPECTION AND INSURANCE COMPANY.


The Hartford Steam Boiler Inspection and Insurance Company makes the
following report of its inspections in January, 1871:

During the month, there were 522 visits of inspection made, and 1,030
boilers examined--853 externally and 363 internally, while 106
have been tested by hydraulic pressure. Number of defects in all
discovered, 431, of which 163 were regarded as dangerous. These
defects were as follows: Furnaces out of shape, 24--3 dangerous;
fractures, 47--25 dangerous; burned plates, 29--14 dangerous;
blistered plates, 54--10 dangerous; cases of sediment and deposit,
97--18 dangerous; cases of incrustation and scale, 70--24 dangerous.
To show how little attention is paid to the internal condition of
boilers by incompetent engineers, we copy the following from a letter
of one of our inspectors:

"In one tubular boiler I found sediment in the back end, eight inches
deep, and extending forward more than four feet. It seemed to be an
accumulation of fine scale cemented together, so that it was necessary
to break it up with a hammer and chisel before it could be removed.
The engineer said _he had cleaned the boilers only three days before_,
and objected to my making another examination. This is one of the
many cases we find, where the proprietor trusts everything about his
boilers to his engineer, supposing him to be reliable."

With such accumulation of sediment and deposit, is it any wonder that
sheets are burned? A careful engineer will understand, if the feed
water be impure, that he must blow down two or three inches every day,
or oftener, that the sediment may be removed as it accumulates, and
then an internal examination once in two weeks, or once a month, will
insure a clean boiler.

Cases of external corrosion, 26--10 dangerous; cases of internal
corrosion, 17--5 dangerous; cases of internal grooving, 28--11
dangerous; water gages out of order, 50; blow-out apparatus out of
order, 15--7 dangerous; safety valves overloaded, 40--12 dangerous;
pressure gages out of order, 54--6 dangerous, varying from -15 to
+8 pounds. (We have found several gages entirely ruined from being
frozen). Boilers without gages, 4; cases of deficiency of water,
5--1 dangerous; broken braces and stays, 31--7 dangerous; boilers
condemned, 2--both dangerous.

Two engineers were found drunk on duty, and promptly discharged. There
were 9 serious explosions during the month, by which 99 persons were
killed, and 6 wounded. Eighty-seven of the killed were passengers on
the ill-fated steamer _H.R. Arthur_, on the Mississippi River. Many
were drowned, and some burned, but the origin of the calamity was the
bad quality of the boilers, which a careless management was unable
to detect. The upper and fore part of the boat was blown away by the
exploded boilers, and, to add to the horror, what remained took fire.

None of these exploded boilers were under the care of this company.

       *       *       *       *       *


Five ore-roasting furnaces are in full blast in Nevada.

       *       *       *       *       *




IMPROVED COMPOUND SPIRAL CAR SPRING FOR RAILWAY CARRIAGES.


Our engravings illustrate an improved compound car-spring, which
appears to possess all the requisites of a first-class spring,
combining in its construction extreme simplicity with great strength,
and a feature whereby the power of the spring increases with increase
of the load, and _vice versâ_, so that its flexibility remains nearly
constant for all loads.

Fig. 1 is a perspective view of this spring, with a portion of the
side of the case broken out to show the interior arrangement of the
spiral springs. Fig. 2 is a section of the compressing plate. Fig. 3
is a plan view, showing the arrangement of the tubes which enclose the
springs.

[Illustration: POTT'S' SPIRAL CAR SPRING FOR RAILWAY CARRIAGES.
_Fig. 1       Fig. 2        Fig. 3_]

The case is cast in two pieces. Its vertical wall is cast in a single
piece, and has at the top a flange or bead extending inwardly, against
which the compressing plate abuts when the spring is not compressed,
as shown in Fig. 2. A bottom plate completes the case.

The spiral components of the spring are inclosed in tubes, as shown in
Figs. 1 and 3. It is not deemed essential that these tubes should be
seamless, or that their edges, brought together in bending, should be
soldered, brazed, or welded. They act merely as guides to compel the
component springs to expand or contract in vertical lines, and need
only be strong enough for that purpose.

The compressing plate is formed with concentric steps or ledges,
as shown in Fig. 2, so that with light loads, only a portion of the
component spirals act. With a heavier load a new series of spirals is
brought into action, and so on, till the spring is loaded to its full
capacity. This feature is novel, and as important as novel, as it
gives the spring a far more easy and flexible carriage, with light
loads, than would be the case if all the spirals were permitted to
act.

In putting the spring together, the vertical part of the case is
inverted. The compressing plate is then placed within the case,
resting upon the inner flange of the case above described. The tubes
with their inclosed springs are then arranged in position, as shown in
the plan view, Fig. 3. The bottom plate of the case is then placed in
position, and held to its place by lugs and rivets, as shown in Fig.
1; the spring is then ready for use.

The employment of tubes in the manner described, enables springs of
the greatest practical length to be used, without the sectional or
division plates met with in other spiral car springs. A greater
and easier movement is therefore obtained. These springs can, it
is claimed, compete in price with any spring in market, and are
guaranteed by the manufacturers. Patented through the Scientific
American Patent Agency, December 27, 1870, by Albert Potts, whom
address for further information, No. 490 North Third street,
Philadelphia, Pa.

       *       *       *       *       *


PORTABLE WRITING AND COPYING CASE.

This device is the invention of A. G. Buzby, of Philadelphia, Pa. It
is a combined writing and copying case. Besides the usual recesses
or chambers for pen, ink, paper, etc., it is provided with a book of
copying paper, in which copies of important letters may be made, by
damping the letters in the usual way, and pressing them between the
leaves of the copying book; or the transfer paper may be used, so that
the letter will be copied as it is written, if preferred.

[Illustration]

       *       *       *       *       *




HOW WALKING STICKS ARE MADE.


Sticks are manufactured both from large timber of from two to six
feet girth, and from small underwood of about the thickness of a man's
thumb. The timber, which is chiefly beech, is first sawed into battens
of about three feet in length and as many inches in width; and
from each of these battens two square sticks, with square heads are
afterwards cut in opposite directions, so that the middle portion
is waste wood. The corners of each are afterwards rounded off by a
planing process called "trapping," and the square head is reduced, by
a small saw, to a curve or rectangular bend, so as to form a handle.
When the sticks are brought in this way to the exact size and pattern,
they are polished with great care, are finely varnished, and packed
in boxes or bundles for the market. Many sawn sticks, however, are
supplied with bone and horn handles, which are fastened on with glue;
and then of course there is less wood waste, as a larger number of
them may be cut from one batten.

A very different process takes place in the manufacture of sticks
from small underwood, in which there is no sawing required. The rough
unfashioned sticks, which are generally of hazel, ash, oak and thorn,
are cut with a bill in the same way as kidney bean sticks, and are
brought to the factory in large bavins or bundles, piled on a timber
tug. There must of course, be some little care in their selection, yet
it is evident that the woodmen are not very particular on this score,
for they have in general an ungainly appearance; and many are so
crooked and rough, that no drover or country boy would think it worth
while to polish the like of them with his knife. Having arrived at
this place, however, their numerous excrescences are soon pruned away,
and their ugliness converted into elegance. When sufficiently seasoned
and fit for working, they are first laid to soak in wet sand, and
rendered more tough and pliable; a workman then takes them one by one,
and securing them with an iron stock, bends them skillfully this way
and that, so as to bring out their natural crooks, and render them at
last all straight even rods. If they are not required to be knotted,
they next go to the "trapper," who puts them through a kind of
circular plane, which takes off knots, and renders them uniformly
smooth and round. The most important process of all is that of giving
them their elegantly curved handles, for which purpose they are passed
over to the "crooker." Every child knows that if we bend a tough stick
moderately when the pressure is discontinued, it will soon fly back,
more or less, to its former position; and if we bend it very much,
it will break. Now the crooker professes to accomplish the miracle of
bending a stick as it might be an iron wire, so that it shall neither
break nor "backen." To prevent the breaking, the wood is rendered
pliant by further soaking in wet sand; and a flexible band of metal
is clamped down firmly to that portion of the stick that will form the
outside of the curve; the top end is then fitted into a grooved iron
shoulder which determines the size of the crook, the other end being
brought round so as to point in the opposite direction; the metal
band during this process binding with increasing tightness against the
stretching fibers of the wood, so that they cannot snap or give way
under the strain. The crook having been made, the next thing is to fix
it, or remove from the fibers the reaction of elasticity, which would
otherwise, on the cessation of the bending force, cause it to backen
more or less, and undo the work. In the old process of crooking by
steam, as timber bending is effected, the stick was merely left till
it was cold to acquire a permanent set; but in the new process, a more
permanent set is given by turning the handle about briskly over a jet
of gas. The sticks being now fashioned, it only remains to polish
and stain or varnish them; and they are sometimes scorched or
burned brown, and carved with foliage, animal heads and other
devices.--_Chambers' Journal_.

       *       *       *       *       *


FLOWERING OF THE VICTORIA REGIA IN THE OPEN AIR.--Joseph Mager, Esq.,
has succeeded in flowering the Victoria lily, in his pond in England.
The pond is perfectly open, but the water is heated by hot water pipes
coming from a boiler near the pond, carefully concealed. The seeds
of the Victoria were planted in May last, and the first flower was
produced Sept. 10th. Afterwards seven other flowers opened. The plant
has eight leaves, of which the largest is five feet two inches in
diameter. Mr. Mager has also succeeded in flowering a large number of
other tropical lilies in his pond.

       *       *       *       *       *


JUTE, a material largely used in combination with hemp, for making
cordage, sacking, mats, and carpets, is produced in India to the
extent of 300,000 tuns per annum. The scarcity of fuel prevents its
manufacture on the spot, except by the rudest and most primitive
means, so that the bulk of the growth is sent to Great Britain.

       *       *       *       *       *




VENTILATION OF THE LIVERPOOL TUNNEL.


This tunnel, which forms an ascending incline of a mile and a quarter
length from the terminal station in Lime-street London and N. W.
Railroad, was worked until recently by a rope and stationary engine,
to avoid fouling the air of the tunnel by the passage of locomotives;
but the increase of the traffic having necessitated the abandonment of
the rope and the substitution of locomotives for bringing the trains
up through the tunnel, it became requisite to provide some efficient
means of ventilation for clearing the tunnel speedily of the smoke and
steam after the passage of each train. A large exhausting fan has been
designed by Mr. John Ramsbottom for this purpose, which works in a
chamber situated near the middle of the length of the tunnel, and
draws the air in from the tunnel, through a cross drift; discharging
it up a tapering chimney that extends to a considerable hight above
the surface of the ground over the tunnel. The fan is about thirty
feet diameter, and is made with straight radial vanes; it revolves
on a horizontal shaft at a speed of about forty-five revolutions per
minute, within a brick casing, built concentric with the fan for the
first half of the circumference, and afterwards expanding gradually
for discharging into the base of the chimney, the air from the tunnel
being drawn in at the center of the fan at each side, and discharged
from the circumference of the fan by the revolution of the vanes.
The engine driving the fan is started by telegraph signal at each
departure of a train from the terminal station, and the fan is kept
running until the discharge from it becomes quite clear, showing that
no steam or smoke remains in the tunnel; this is usually the case in
about eight minutes after the time of the train entering the lower end
of the tunnel, the passage of the train through the tunnel occupying
about three minutes. The fan draws air in at both ends of the tunnel
simultaneously, and begins to clear the lower end immediately upon the
train entering; the clearing of the upper end commences as soon as the
train has passed out of the tunnel, and as the fan is situated nearer
the upper end of the tunnel than the lower, the clearing of both
lengths is completed almost simultaneously. The fan is so constructed
as to allow an uninterrupted passage through it, for the air, whilst
the fan is standing still; and the natural ventilation thus obtained
by means of the large chimney is found sufficient for clearing the
tunnel during the night and some portion of the day, without the fan
being worked at those times. This natural ventilation is aided by the
engine exhaust and the boiler discharging into the chimney. The fan
has now been in regular operation for three-quarters of a year, and
has been found completely successful.

       *       *       *       *       *




IMPREGNATING WOOD WITH TAR OR OTHER PRESERVING MATERIAL.


The preservation of wood is a problem which is attracting increased
attention, as year by year diminishes the material supply of timber,
and consequently gradually increases its price. Among other methods
employed, the impregnation of wood by the vapors of tar, creosote,
petroleum, etc., has been tried, and one of the practical difficulties
met with has been the obtaining of suitable apparatus for the purpose.

[Illustration]

The engraving annexed is an invention intended to supply this want.
The wood is inclosed, in a tank kept hot by a steam jacket which
surrounds it, as shown. A boiler at one end is used to heat the
substance with which it is desired to impregnate the wood. An air pump
is also employed to remove the steam, generated in the heated timber,
and the air from the tank. The pores of the wood being thus rendered
vacuous, the hot liquid or vapors from the heating tank readily
penetrate the entire substance, and thoroughly impregnate it. This
apparatus is the invention of George Pustkuchen, of Hoboken, N. J.

       *       *       *       *       *




BOARDMAN'S COMBINED TOOL.


This tool, of which our engraving is a good representation, comprises
a screw wrench, a pipe wrench, a hammer, a nail claw, a screw-driver,
and a bit handle, or socket wrench.

The bit handle is the entire tool, the square socket or opening being
made in the end of the handle, in which the shanks of bits may be
inserted.

The screw driver is formed on the end of the screw bar, attached to
the outer jaw of the wrench, and is taken out from the hollow of the
handle when required for use.

The use of the other parts of the tool will be apparent from the
engraving.

The tool is very compact, and has this advantage over the ordinary
screw wrench, that its leverage increases as it is opened to receive
nuts of larger size.

[Illustration]

This invention is protected by two patents, dated respectively, May
30, 1865, and July 10, 1866.

For further information address B. Boardman & Co., Norwich, Conn.

       *       *       *       *       *




BELT TIGHTENER.


[Illustration]

This instrument will be found of great service in bringing together
the ends of belts, the weight of which is so great that they cannot
be held together by the hand while lacing. A strap engages with holes
made in the belt, at the back of the holes punched for lacing, the
tightening strap being provided with claws or hooks, as shown. A winch
axle and ratchet, adjusted in a frame as shown, are then employed
to pull the ends of the belt together and hold them firmly till the
lacing is completed.

This is the invention of T. G. Stansberry, of Medora, Ill. Patented in
September, 1867.

       *       *       *       *       *




SOME THINGS I DON'T WANT IN THE BUILDING TRADES.


I don't want my house put in repair, or rather out of repair, by a
master who employs "Jacks of all Trades."

I don't want my foreman to tell me too much at one time about the
faults of the workmen under him, as I may forget asking him about
himself.

I don't want a builder or carpenter to give a coat of paint to any
joinery work he may be doing for me, until I have examined first the
material and workmanship.

I don't want any jobbing carpenter or joiner, whom I may employ, to
bring a lump of putty in his tool basket. I prefer leave the use of
putty to the painters.

I don't want jobbing plumbers to spend three days upon the roof,
soldering up a crack in the gutter, and, when done, leaving fresher
cracks behind them. The practice is something akin to "cut and come
again."

I don't want a contractor to undertake a job at a price that he knows
will not pay, and then throw the fault of his bankruptcy on "that
blackguard building."

I don't want any more hodmen to be carrying up the weight of
themselves in their hod, as well as their bricks; I would much prefer
seeing the poor human machines tempering the mortar or wheeling the
barrow, while the donkey engine, the hydraulic lift, or the old gray
horse, worked the pulley.

I don't want house doors to be made badly, hung badly, or composed of
green and unseasoned timber.

I don't want houses built first and designed afterwards, or, rather,
wedged into shape, and braced into form.

I don't want to be compelled to pay any workman a fair day's wages for
a half day's work.

I don't want an employer to act towards his workmen as if he thought
their sinews and thews were of iron, instead of flesh and blood.

I don't want any kind of old rubbish of brick and stone to be bundled
into walls and partitions, and then plastered over "hurry-skurry."
Trade infamy, like murder, will out, sooner or later.

I don't want men to wear flesh and bone, and waste sweat and blood,
in forms of labor to which machinery can be applied, and by which
valuable human life and labor can be better and more profitably
utilized.

       *       *       *       *       *




CORRESPONDENCE.

_The Editors are not responsible for the opinions expressed by their
Correspondents._


       *       *       *       *       *


ACTION OF THE RECIPROCATING PARTS OF STEAM ENGINES.

MESSRS. EDITORS:--I have hesitated about the propriety of replying to
the criticisms of your correspondent, J. E. Hendricks, upon my paper,
on the action of the reciprocating parts of steam engines. It is not
to be expected that a truth so opposed to commonly received
notions--the reception of which requires so much to be unlearned--should
at once receive the assent of every one. Some odd fancies on the
subject are likely to be ventilated first.

But your correspondent touches the root of the matter, and perhaps the
fact questioned by him should be more clearly placed beyond dispute.

I will dismiss the introductory part of his letter, merely observing
that his "logical inference" is quite gratuitous and unwarranted. He
says himself that its absurdity is obvious, in which I quite agree
with him.

The real question is this: What is the figure representing the
acceleration of the motion of a piston, controlled by a crank which
revolves with a uniform velocity? I stated it to be a right-angled
triangle, and indicated, as I supposed, clearly enough, a simple
method by which this could be shown. Your correspondent claims that
the calculation, according to my own rule, gives a figure of a totally
different form, and one that shows the acceleration, as well as the
motion, to be reduced to zero at the commencement of the stroke. Let
us see. Let the straight line, AJ, in the following figure, represent
half the stroke of the piston, and let the distances, AB, AC, etc., on
this line, represent the versed sines of 10°, 20°, etc., up to 90°, or
the motion of the piston while the crank is moving through these arcs.
At the points A, B, C, etc., erect the perpendiculars, Aa, Bb, Cc,
etc., and let the length of each of these ordinates represent the
acceleration imparted in a given time at that point of the stroke.
Then will AJ be to Aa as IJ is to Ii, as HJ is to Hh, etc., showing
that the straight line, aJ, connects the extremities of all the
ordinates, and that the triangle, AJa, represents the acceleration of
the motion of the piston, from the commencement to the middle of the
stroke.

[Illustration]

The following table will enable any one to make the calculations
proving the truth of the above proposition:

Degrees.  Versed sine.     Motion for 10°   Acceleration during 1°.
   0°          .0000000                     _Aa_  .0003046
  10°   _AB_   .0151922   _AB_  .0151922    _Bb_  .0003001
  20°   _AC_   .0603074   _BC_  .0451152    _Cc_  .0002862
  30°   _AD_   .1339746   _CD_  .0736672    _Dd_  .0002638
  40°   _AE_   .2339556   _DE_  .0999810    _Ee_  .0002332
  50°   _AF_   .3572124   _EF_  .1232568    _Ff_  .0001958
  60°   _AG_   .5000000   _FG_  .1427876    _Gg_  .0001523
  70°   _AH_   .6579799   _GH_  .1579799    _Hh_  .0001041
  80°   _AI_   .8263518   _HI_  .1683719    _Ii_  .0000529
  90°   _AJ_  1.0000000   _IJ_  .1736482    _Jj_  .0000000

The method of obtaining the decimals representing the acceleration for
1°, at any point, was fully explained in the paper, and compared with
the similar method of showing the uniform acceleration of a body acted
on by a constant force. The ordinary tables in the hand-books, going
only to five places of decimals, are of no use for these computations.

I would suggest a practical experiment. Let any one having an engine
running at a good speed, loosen the crank pin brasses a little, so
that, at starting, it will thump heavily. Let the engine be lightly
loaded, so that only a small portion of the boiler pressure will need
to be admitted to the cylinder. As its speed increases, the thump
will die away; and, if at its full speed, the pressure of the steam
admitted is not so great as to overcome the centrifugal strain of the
reciprocating parts on the crank, as it passes the centers, the engine
will revolve in silence. Any one can ascertain, by the rule given
in the note to the paper, just what pressure can be admitted without
causing a thump, or this can be found by a little experimenting. I am
running an engine which does not thump with loose crank pin brasses,
under eighty pounds pressure, admitted sharply on the centers.

Charles T. Porter.

       *       *       *       *       *


ANSWER TO PRACTICAL PROBLEM.

MESSRS. EDITORS;--I submit the following solution of "Practical
Problem" on page 147:

Given AB, arm, C, arm, D, chord of half angle of oscillation of arm,
D, and angles of arms, with line AB.

To find angles, BAc', ABb, and length of link, E.

1. As the length of arm, D, is to the chord of arc, ab, divided by
2, so is the radius to the sine angle oscillation of arm, D, divided
by 4.

2. 360° is to the whole circumference as the angle bBa is to the
length of arc ab.

3. Now arc ab is equal to arc a'c'.

4. The whole circumference is to 360° as the length of arc a'e' is
to the angle oscillation of C divided by 2.

5. Half angle oscillation, C, taken from angle BAa' is equal to angle
BAc'.

6. Half angle oscillation, D, taken from angle ABa is equal to angle
ABb.

7. The diagonal of the rectangle formed by the (sum of the sines of
the angles of the arms with AB) into (AB--sum of cosines of same) will
be the length of link, E.

[Illustration]

G. R. NASH, Civil Engineer.

North Adams, Mass.

[We have received other solutions of this problem, but as this covers
the ground in a very simple manner, we think it will be sufficient.
Those forwarding the solutions not published will accept our thanks
and assurances that it is not because they lack merit that they are
declined.--EDS.

       *       *       *       *       *


RECIPROCATING PARTS OF STEAM ENGINES.

MESSRS. EDITORS:--In one of the late numbers of your journal, you
publish a paper, read by Mr. Porter before some learned society in New
York, on something about the possibility or practicability of running
a steam engine at a high rate of speed, and claiming to give a
scientific explanation of the why and wherefore. Now, scientifically,
I know nothing about a steam engine; practically, I know how to stop
and start one. Therefore, you will understand that what I say is not
as coming from one who claims to be wise above what is written, but as
simply being a statement of the case, as it appears to one who wants
to learn, and takes this way to draw out the truth. A scientific
theory, invested with all its sines, coefficients, and other
paraphernalia, is a very pretty thing to look at, no doubt, for those
who understand it, and, when properly applied, is invaluable; but
when, as in this case, a practical question is to be decided, by the
aid of a scientific demonstration, it will not do to throw aside the
main elements of the problem, or any, in fact, of the minor points, no
matter how trivial they may appear.

Mr. Porter's labors were strictly of a scientific nature. He starts
out with the proposition that what he is about to explain is very
simple, and very likely it is; but, for one, I can't see it, and I
want more light. He says that it takes a certain number of pounds to
overcome the inertia of the reciprocating parts of a certain weight,
to give it a certain speed. What is inertia? He says, "we will not
take into account the friction of parts." Now, my understanding of
this point is, that friction is practically one of the main elements
in the problem. How can we hope to obtain a correct solution when he
rubs out one of the terms of the equation? What is friction doing all
the time, while he is theoretically having his reciprocating parts
storing up power and then giving it out again, just at the right time,
and in the right quantity?

What an immense amount of iron has been wasted by being cast into fly
wheels, when a fraction of the amount, if only put into cross heads,
would render fly wheels unnecessary!

Mr. Porter stops short in his discussion. He should have added a table
giving the proportionate length of stroke, weight of parts, and number
of revolutions required to produce the effect of an engine running at
a high speed, without the least fraction of inequality in the strain
on the crank, and then the sun would have fairly risen in the "dawn of
a new era for the steam engine." But, as it is so very simple, we can
all figure it out for ourselves.

In the diagram Mr. Porter gives, to illustrate the travel of the
piston, he wets his finger and draws it over another term in the
equation (a method of elimination not taught by Hutton, Davies, and
other mathematicians). It is a quick way, but is it correct? He says,
"the distance traveled by the piston is the versed sine of an angle
formed by a line from the center of the crank pin, in any part of its
stroke to the center of the circle described by the crank pin, leaving
out of the calculation the angular vibration of the connecting rod."
What he means by the "angular vibration," I do not know. He is wrong
in the statement. If he will think of it he will see it. If he meant
to say that the piston's travel was measured by the versed sine of the
angle formed by the connecting rod and the line of horizontal centers,
he is wrong again, yet nearer the truth than before, just as the
proportion between the length of the connecting rod and the half
diameter of the circle described by the crank pin. This can quickly
be seen by supposing the connecting rod to be detached, and allowed
to fall down on the center line, at any part of the stroke. If he
understood this (as no doubt he did), he should not ignore the facts.

What I am aiming at is this. When a man attempts to demonstrate a
thing mathematically, he must take into his calculation everything
essentially connected with the problem, just exactly as it is, and not
as he would have it; otherwise, he cannot, by any possibility, attain
a correct result. When he claims, as now, the practicability of
running engines at a high speed, I think he is claiming too much.
Build an engine of proper materials, make it strong, and fit
everything as it should be, balance crank and fly wheel to a nicety,
keep everything snugly in its place, and the terrors of a quick stroke
vanish.

S. W. H.

       *       *       *       *       *


TEST FOR WHITE LEAD.

MESSRS. EDITORS:--I have read, with much interest, Dr. Chandler's
colorimetric test of the purity of white lead, as published in the
SCIENTIFIC AMERICAN sometime ago. I enclose another test, which,
though not new, is of value to all using white lead on account of its
simplicity and effectiveness. It has been in use here for nearly two
years, and has been found reliable. Having never seen it in print, I
have tried to put it in as simple words as possible.

FELIX MCARDLE, Analytical Chemist.
St. Louis, Mo.

Take a piece of firm, close grained charcoal, and, near one end of it,
scoop out a cavity about half an inch in diameter and a quarter of an
inch in depth. Place in the cavity a sample, of the lead to be tested,
about the size of a small pea, and apply to it continuously the
blue or hottest part of the flame of the blow pipe; if the sample be
strictly pure, it will in a very short time, say in two minutes, be
reduced to metallic lead, leaving no residue; but if it be adulterated
to the extent of ten per cent. only, with oxide of zinc, sulphate of
baryta, whiting or any other carbonate of lime, (which substances are
now the only adulterations used), or if it be composed entirely of
these materials, as is sometimes the case with cheap lead, it cannot
be reduced, but will remain on the charcoal an infusible mass.

Dry white lead, (carbonate of lead) is composed of metallic lead,
oxygen and carbonic acid, and, when ground with linseed oil, forms the
white lead of commerce. When it is subjected to the above treatment,
the oil is first burned off, and then at a certain degree of heat, the
oxygen and carbonic acid are set free, leaving only the metallic lead
from which it was manufactured. If, however, there be present in the
sample any of the above mentioned adulterations, they cannot of course
be reduced to metallic lead, and cannot be reduced, by any heat of
the blow pipe flame, to their own metallic bases; and being intimately
incorporated and ground with the carbonate of lead, they prevent it
from being reduced.

It is well, after blowing upon the sample, say for half a minute, by
which time the oil will be burned off, to loosen the sample from the
charcoal, with a knife blade or spatula, in order that the flame may
pass under as well as over and against it. With proper care the lead
will run into one button, instead of scattering over the charcoal,
and this is the reason why the cavity above mentioned is necessary. A
common star candle or a lard oil lamp furnishes the best flame for use
of the blow pipe; a coal oil lamp should not be used.

By the above test, after a little practice, so small an adulteration
as one or two per cent. can be detected; it is, however, only a test
of the purity or impurity of a lead, and if found adulterated, the
degree or percentage of adulteration cannot be well ascertained by it.

Jewellers usually have all the necessary apparatus for making the
test, and any one of them can readily make it by observing the above
directions, and from them can be obtained a blow pipe at small cost.

If you have no open package of the lead to be tested, a sample can
most easily be obtained by boring into the side or top of a keg with
a gimlet, and with it taking out the required quantity; care should be
used to free it entirely from the borings or particles of wood, and it
should not be larger than the size mentioned; a larger quantity can be
reduced, but of course more time will be required, and the experiment
cannot be so neatly performed.

       *       *       *       *       *


HOW TO BUILD A CHIMNEY.

MESSRS. EDITORS:--I am satisfied that a great many fires originate
through poorly constructed chimneys; and, although not a bricklayer
by trade, I would offer a few hints how to construct a fire-proof
chimney. Let the bed be laid of brick and mortar, iron, or stone; then
the workman should take a brick in his left hand, and with the trowel,
draw the mortar upon the end of the brick, from the under side, and
not from the outside edge, as is usual. Then, by pressing the brick
against the next one, the whole space between the two bricks will be
filled with mortar; and so he should point up the inside as perfectly
as the outside, as he proceeds.

By drawing the mortar on the edge of the brick, the space between
the ends will not always be entirely filled, and will make (where the
inside pointing is not attended to) a leaky and unsafe chimney, which,
if not kept clear of soot, will, in burning out, stand a good chance
of setting the building on fire. The best thing that I know of, to
put the fire out in a burning chimney is salt; but the matter of first
importance, after having a chimney properly constructed, is to keep it
clean.

AUSTIN B. CULVER.
Westfield, N. Y.

       *       *       *       *       *


CRYSTALLIZED HONEY.

MESSRS. EDITORS:--Please allow me to say to the querist who, through
your columns, asks what to do with crystalline honey, that if he will
"doctor" it with almost any artificial honey of the day, it will not
become like lard in cold weather, which change is a natural proof that
it is pure. For almost any purpose, pure honey is preferable to that
which has been adulterated, but purity is a minor consideration with
many.

Next we shall hear of some fastidious customer who objects to pure
lard, because it looks white when cold. To such we would recommend
lard oil as a great improvement, especially for cooking purposes.

A. M. B.
Louisville, Ky.

       *       *       *       *       *

[For the Scientific American.]




RAMBLES FOR RELICS.

NUMBER II.


At a depth of fifteen feet, we were about to suspend our labors,
supposing from the nature and uniformly dark color of the earth,
that we had reached the surface of the alluvium, when a sign of the
inevitable wood and bark layer was seen in a crevice. An excavation,
five or six feet, into the wall, revealed the skeleton of a man laid
at length, having an extra coverlid of wooden material. Eighteen large
oblong beads, an ax of polished green stone, eleven arrow points, and
five implements of bone (to be described) were deposited on the
left side; and a few small beads, an ornamental shell pin, two small
hatchets, and a sharp-pointed flint knife or lance, eight inches long,
having a neck or projection at the base, suitable for a handle, or for
insertion in a shaft, on the right side. The earth behind the skull
being removed, three enormous conch shells presented their open
mouths. One of my assistants started back as if the ghost of the
departed had come to claim the treasure preserved, in accordance with
superstitious notions, for its journey to the "happy lands." The alarm
seemed to be a warning, for at the moment the embankment, overloaded
on one side, caved in, nearly burying three workmen, myself, and a
spectator. Our tools being at the bottom of the heap, and the wall on
the other side, shaken by the falling earth, giving tokens of a change
of base, our prospects of a ready deliverance were not very hopeful.
The bystanders, however, went to work with their hands, and we were
soon relieved, not without casualty, the spectator having the worst of
it. Struggling to extricate himself, instead of abiding his time, he
dragged one leg out of the pile shorter than the other.

The occurrence of marine shells in a burial depository, especially of
the varieties pyrula and oliva, four or five hundred miles from the
Gulf and that portion of the Southern coast where the mollusks exist,
bears upon the question of migration and tribal intercourse, and
the commercial value of these articles. Obtained from a distance and
regarded as precious commodities, they were used in exchange, for the
material of ornaments, and for choice utensils. Only two or three of
these shells have been found in a perfect condition, but defective
ones are frequent, with fragments, "cuttings," and various trinkets
made out of them--such as ornamental pins, needles, crosses, buttons,
amulets, engraved plates, and beads. From one of the specimens
recovered from the mound sepulchre, the spire and columella had been
removed, leaving a hollow utensil. It would have been suitable for
a water vessel, but for a hole in the bottom, which had furnished a
button-shaped ornament, or piece of money, which was found with the
relic, and exactly corresponded to the orifice. The twirled end of the
shell, however, had been improved for a handle by shallow cavities,
one on the inside slanting from the middle longitudinal line, and one
crossing that line at right angles on the convex side, so as to be
fitted to the thumb and fore finger of the left hand, suggesting a use
of the implement as a shield, or a mask held before the face. Adair
speaks of large shells in use by the Indians of his time (1735),
suspended about the neck for shields, and regarded as badges of
priestly dignity.

A trench was dug on the east side of the mound, nearly corresponding
in dimensions to the one on the west side, making the length of the
whole excavation, including the central cavity, thirty-two feet.

In the last opening, eight skeletons were exhumed; the mode of burial
was the same throughout. The only article of value recovered was a
curiously wrought pipe of stone, having a "figure head" representing
the human face, which I have put down in a list of "articles stolen,"
and which the thief can describe better than the writer. After filling
up all the gaps, and levelling the surface to suit the taste of the
proprietor, we closed our labors on the mound in the Bent.

Of the skulls collected, it is sufficient to say that they belong to
the "short heads," the length and breadth having a comparative medium
proportion, a common form of cranium in the mounds of Tennessee.

Of stone implements I specify an ax of serpentine, ten inches long,
two thick, and four broad, having plain sides and a straight edge
ground down on both of the flat faces; hatchets ("tomahawks") of
green stone, flint, and diorite, from five to eight inches long, with
rounded faces and sides, contracted to an edge at one end, and to a
flat heel at the other; a wedge of black slate, seven inches long and
half an inch thick, of a square finish on the faces and sides and at
the heel, which was diminished two inches, as compared with the length
of the edge; hatchets with a serrated edge at each end, plane on both
sides, convex on one face and flat on the other.

With one skeleton was deposited a "set of tools," eight in number, of
the species of rock before mentioned, varying in length from two to
eight inches. Their peculiarity consists in a variety of shapes--no
two being precisely alike--and in their fitness to various uses,
such as carving, hacking, paring, and grooving. The smallest of them,
having a square finish, was held by the thumb and two fingers, and is
suitable for cutting lines and figures in wood and shells. Specimens
of this art were furnished from the mound. The largest number might
serve for hatchets, chisels, and gouges. One had been ground in the
form of a cylinder five inches long and an inch thick, and then cut
an inch on two sides to an edge, and worked into a handle with a round
bead, from the center of the elliptical faces. It might be used for
chipping wood and stone. One answered the purpose of a cold chisel;
another was somewhat similar, but had a hollow face reduced to a
curved edge for grooving. These polished instruments, wrought with
much care, seemed intended for use by the hand rather than for
insertion in a handle or socket, or attachment to a shaft by means
of a strap or withe. Only one was perforated. The drilling through
granite, quartz, and diorite, without the use of metal, was a severe
labor, even for savage patience. A long knife of silex, with a wrought
handle, lance heads, leaf shaped, of the same material, of beautiful
workmanship, arrow points of fine finish, furnished, with others
before mentioned, an assortment of arms. Several flint points, though
only an inch long, were curved like a cimeter, and used probably as
flaying instruments. True disks, of various mineral substances, from
an inch to five inches in diameter, having convex faces, complete the
list of stone implements. Those of bone comprise several like hollow
chisels, sharpened at one end, and pierced through one face, near the
other extremity, so as to be fastened to a handle; these were used
for dressing skins. One was formed like a poniard, with a worked hilt.
With these may be connected arrow heads and sharp pointed weapons of
the worked antlers of the stag, and tusks of the wild boar.

Of ornaments, I noticed pins used for dressing the hair, made of the
columns of large sea shells. The head is generally round, sometimes
oval, from an eighth to a half of an inch in diameter, retaining the
diagonal groove of the pillar from which it is made. The stems vary
in length from one to six inches. It would be tedious even to classify
ornamental beads and buttons of shell work, such as are usually found
in the mounds. These trinkets are perforated, and, in addition to
their being articles of dress, were used probably as "wampum," the
currency of the recent Indians.

A miscellaneous collection includes a hematite stone, wrought in
the shape of a cup weighing half a pound; when rubbed or ground it
furnished the war paint of the savages; also the extremity of a copper
tube, two inches long; needles in bone and shell, from an inch to
six inches long, with grooves round the head, to serve the purpose of
eyes; and plates of mica. The use of mica plates, which are found of
large size in some of the Western mounds, has excited some inquiry.
Of a certain thickness, they make good mirrors. Beside their use
for ornamental purposes, they were probably looking-glasses of the
beauties of the stone age. There was also found a pipe of soap stone,
having a stem five inches long, and a bowl with a broad brim, like a
Quaker's hat.

Of earthenware, there was an endless variety of fragments of the usual
black, grey, or red compressed clay, mixed with pulverized shells or
stones. One kind I have never seen described. The sherds had a red
coating on both sides, an eighth of an inch in thickness, evidently
not a paint or a glaze. The red coloring might have come from the
pottery being burnt in the open air, instead of baked in a furnace,
were not the layer of uniform thickness and of homogeneous paste,
unlike the material of the vessel, which was a gray mixture of clay
and particles of shells.

I give the above memoranda to the general fund of information,
touching a subject that invites inquiry on account of its novelty and
ethnological importance. Every examination of the monumental remains
of the ancient Americans brings to light some new feature in structure
or type of rudimental art. And since archæology has become a science,
investigators, for half a century, may be looking about for facts to
complete the system auspiciously introduced by the antiquarians of
Northern Europe, and advanced in our own country by the researches
of Caleb Atwater (_Archæologia Americana_) and by those of the
Smithsonian contributors to knowledge, especially Squier and Davis.
RAMBLER.

       *       *       *       *       *


A SMALL WATER WHEEL.--There is in the town of Meriden, Conn., a
Leffel double turbine wheel, running under 240 feet fall and driving
a manufactory. It uses only about one-half of a square inch of water,
and runs at the marvelous speed of 3,000 revolutions per minute, or 50
revolutions per second, which is by far the most rapid rate of motion
ever imparted to a water wheel. This is, also, beyond comparison the
greatest fall applied to the propulsion of a wheel in America. The
wheel at Meriden is of the most diminutive size, scarcely exceeding in
dimensions the old-fashioned "turnip" watches which our grandfathers
used to carry in their capacious vest pockets. The complete success of
this wheel has attracted much attention and affords further evidence
of the wide range of adaptability of the Leffel turbine.

       *       *       *       *       *

[For the Scientific American.]




SILK CULTURE.

BY W. V. ANDREWS.


A vague notion that silk culture ought to form one of the industrial
pursuits of the American people seems to be prevalent enough; but it
does not take practical hold upon anybody. The nearest approach to
anything practical which we have seen, in late years--excepting, of
course, what has been done in California--occurred in New York in July
last, when a number of gentlemen pledged themselves, according to a
report given in the _Tribune_ of July 30, "to promote the native silk
trade."

The gentlemen present at the meeting represented the most prominent
silk manufacturing and importing houses in this country. What these
gentlemen have since done towards promoting the native silk trade, I
do not know, but, having pledged themselves, it is presumed they have
done something.

At the meeting, of which the _Tribune_ article is a report, dags,
and other things, manufactured from California silk, were exhibited;
and the report goes on to say that "Mr. Warren also exhibited samples
of native and foreign cocoons, and of raw and thrown silk, together
with the common _Cecropia_ and _Bombyx Cynthia_, species of
silkworms which feed upon oak leaves.  *  *  Also the _Bombyx Yamamai_
which feeds upon mulberry leaves; also the _Bombyx Pernyi_, of
which the cocoons are early as good as the cocoons of worms fed upon
mulberry leaves."

I have given this extract, word for word, as it stands in the columns
of the _Tribune_, because it contains more blunders of one kind or
another than I remember ever to have seen in so many words. _Cecropia_
is certainly not very particular as to its food, but it is not an oak
feeder. _Cynthia_ will thrive on nothing except ailanthus, though it
will eat one or two other things, but not oak. The _Yamamai_, on
the other hand, will eat oak, indeed it is its natural food; but Mr.
Warren errs greatly when he says that it will feed on mulberry. The
last clause of the sentence, which says that cocoons of _Pernyi_ are
nearly as good as those of worms fed on mulberry leaves, must be a
sort of entomological joke, of which the point is not discoverable by
me, so I pass it over.

I do not, however, notice this report on account of its grammatical
and entomological mistakes. It is because of the evil effects it may,
and probably will, have on amateur silk culturists, that I notice
it; for most assuredly, failure will be the result of all attempts
to produce silk cocoons by feeding the caterpillars of the different
moths on the food prescribed by Mr. Warren. Any patriotic, money
making farmer, who believes in the _Tribune_, purchasing _Yamamai_
eggs and setting his worms to feed upon mulberry, which they refuse to
eat, and consequently, all die, will probably give up silk culture
as being nothing more or less than a humbug. And thus the cause is
injured.

For several years past, I have made some experiments in the rearing of
the silkworms, giving the result of my experience in the first year in
Vol. II., page 311, of the _American Naturalist_; and of a subsequent
year in the _Entomologist_, for November, 1869.

The paper in the _Naturalist_ is devoted to my experiments with the
ailanthus silkworm, _Samia Cynthia_ (G. & R.), a naturalized species
from the East. In that paper, I have said all that is necessary to
say at present, on that species, except perhaps that I am further
convinced, from the inspection of samples of sewing and other silks,
made from the cocoons of _Cynthia_, that one day it will be reared
very extensively in the United States. It is perfectly hardy, is
double brooded, and may be reared by any one possessed of a few acres
of land, which may be good enough for growing ailanthus trees, but
not good enough to grow any thing else. The labor of a few old men,
or women, or even children, is sufficient for the purpose. The cost is
therefore trifling.

The objection to the cultivation of _Cynthia_ is that the cocoon
cannot be reeled. But it can be carded, and if the Chinese can make
excellent silk goods from it, why cannot we? I suspect, too, that
_Cynthia_ silk can be worked in with cotton, or, perhaps, woolen
goods, adding to their beauty and durability (for it is indestructible
in wear), and thus open up branches of manufacture hitherto unknown.

For manufacturers of coarse goods, I have no doubt that the silk
from our native silk moths, _Cecropia_ and _Polyphemus_, may be used.
Indeed, I believe that M. Trouvelot is of opinion that _Polyphemus_
may fairly enter into competition with _Bombyx mori_, the ordinary
mulberry silkworm. The worm, however, is rather difficult to rear.

In reference, however, to _Bombyx mori_, it is well known that the
silk crop in France and Italy has been reduced greatly, and the price
of silk goods consequently enhanced, by prevalence of disease among
the worms. So much is this the case, that silk breeders have been
obliged to look around for some silk-producing moths whose products
may, at any rate, supplement the deficient crop. _Cynthia_, as already
mentioned as one of these, and two others mentioned by Warren in the
_Tribune_ reports above adverted to, are at present the subjects of
experiment.

My article mentioned before as appearing in the _American
Entomologist_ is mainly devoted to my experiments, and those of my
correspondents, with _Yamamai_, which, as I said before, is an oak
feeder. In Japan, which is its native country, it feeds, in its wild
state, on _Quercus serrata_. Whether that oak be found in America, I
do not know, but it is of little importance, as the worm will feed on
almost any species of oak, although I think that it prefers white oak.
The importance of acclimatizing new species of silk moths is of so
much prospective importance, that I shall devote the remainder of this
article to the consideration of whether _Yamamai_ and _Pernyi_ may not
be naturalized here. Any one, who happens to have the number of the
_Entomologist_ containing the article above alluded to, may find it
worth while to read it, but as many persons may not be able to obtain
that number, I will here repeat the substance of my remarks, adding as
much new matter as subsequent experience has afforded.

The silk from the _Yamamai_ being considered superior to that produced
by any other of the substitute silk moths, great efforts have been
made in Europe to acclimatize it; but, it must be confessed, hitherto
with but slight success. There are exceptions, however, particularly
among amateurs in Germany, sufficient to show that success is
possible. The Baron de Bretton raises about 27,000 cocoons annually.

In this country but little has been done, or attempted, and that
little has not been very successful.

The fact is, that _Yamamai_ is a difficult moth to rear in a country
like this, where in early spring the temperature varies so much; but
that success is possible, I am convinced.

The moth emerges from the cocoon in the latter part of the summer,
copulates, lays its eggs, and of course dies. And now the trouble
commences; that is, with eggs laid, say in Japan, from whence we
mainly get our supplies.

As soon as the egg is laid, the young larva commences its formation,
which in a short time (about one month) is perfected. It lies in the
egg in a quiescent state till early spring. If the egg remain in the
country where it is laid, and is kept at a pretty even temperature,
and free from damp, the caterpillar emerges in a healthy condition.
But if it be removed some thousands of miles, passing in the transit
from heat to cold, and back to heat again: and if, in addition, it
be closely confined in a damp place, with little or no circulation of
air, the egg is attacked by a fungus which sometimes prevents the worm
from emerging at all; or, if it emerge, it is in a sickly condition.
That these conditions obtain in the transit of eggs, from Japan
to Europe, and thence to America, is evident enough; and it may,
therefore, require the efforts of many persons, continued for a long
time, to enable us to acclimatize the _Yamamai_. But this is all that
is required, and I feel confident that ultimate success is certain.

On hatching out, the worm is of a brimstone yellow, and thinly covered
with strong hairs; after the second month it is greenish, with black,
longitudinal streaks, and the thread a dull coral red color. After the
third month it becomes of a fine apple green, with yellow tubercles
on each segment, from which issue a few black hairs. The head and legs
are chocolate brown, the prolegs reddish, and the first segment edged
with pinkish color. The greatest care is necessary, as the spring
advances, to prevent the eggs from hatching before the oak buds
are ready for them, and the temperature must be regulated with the
greatest nicety. If the eggs can be kept somewhere about 50 deg. Fah.,
it would be quite safe; higher than that the mercury should not be
allowed to rise, till you are quite ready for the worms, and, on the
other hand, the eggs should not be allowed to freeze.

On emerging from the eggs, the worms should be allowed either to crawl
to the oak branches, or rather to sprigs obtained for that purpose,
the end of which should be placed in a jar, or bottle, of water, or
the worms may be placed on gently with a camel-hair brush. The leaves
should be well sprinkled with clean water that the caterpillars may
drink.

From some cause, not well understood, the young caterpillars have
a tendency to wander; and if care be not taken many may be lost. To
prevent this, it is well to cover the branches with a gauze bag, tied
tightly around the stems, and close to the bottle. Care must also
be taken that the caterpillars do not find their way into the water,
which they assuredly will if they have the opportunity, committing
suicide in the most reckless manner. If the number of caterpillars be
few, it is a good plan to place them at the outset with their food,
in a wide-mouthed bottle, covering the mouth with gauze. The branches,
particularly if the weather be warm, must still be occasionally
sprinkled, so that the caterpillars may have the opportunity of
drinking. It must be remembered that experiment is necessary in
rearing _Yamamai_, but one thing is ascertained, and that is, that the
worms must not be exposed to direct sunshine, at least not after seven
or eight in the morning. If the spring be warm, I am inclined to think
that a northeastern exposure is the best, and we may sum up by saying,
that comparatively cool and moist seasons are more favorable to
success that hot, dry weather. In America the worms suffer in the
early spring, from the rapid changes of temperature, 40° at 9 A.M.
increasing to 70° in the afternoon and falling off to freezing point
during the night. The worms cannot stand this. They become torpid,
refuse to eat, and consequently die. To prevent this, if the nights
be cold, they must be placed where no such change of temperature can
occur.

It is scarcely necessary to say that an ample supply of fresh food
must be always supplied, but it may not be amiss to say that it is
well, when supplying fresh branches, to remove the worms from the old
to the new. The best way of doing this is to clip off the branch, or
leaf, on which the worm is resting, and tie, pin, or in some way affix
the same to the new branches. If this be not done, they will continue
to eat the old leaf, even if it be withered, and this induces disease.
If the worm has fastened itself for the purpose of moulting, the best
way is to remove the entire branch, clipping off all the dried
leaves before so removing it. These remarks apply, in general, to the
treatment of all silkworms, except _Bombyx mori_.

The results of numerous experiments with _Yamamai_ go to show that it
is, as I said before, a difficult worm to rear; but it has been reared
near New York to the extent of eight hundred cocoons out of sixteen
hundred eggs, and this, although not a remunerative result, is
encouraging.

The Chinese silk moth, _Aulterea Pernyi_, also an oak feeder, has been
successfully raised by me and by others, for several years. Eggs have
been sold to persons in States widely separated, and the results show
that this worm is perfectly hardy.

The moth winters in the cocoon, emerges early in May, if the weather
be warm, pairs readily, and lays from 150 to 200 eggs. These hatch
out in about fourteen days, and like _Yamamai_, always about 5 or 6
o'clock in the morning. It is necessary to be on the alert to catch
them on hatching only, and to remember that they are vagabonds, even
to a greater extent than _Yamamai_. Consequently similar precautions
must be taken.

The worm on emerging from the egg is large, and of a chocolate-brown
color. After the first month it becomes of a yellowish green; head,
pale brown; feet and prolegs of nearly the same color. The body has
numerous reddish tubercles, from which issue a few reddish hairs. At
the base of some of the tubercles on the anterior segments are silvery
patches.

The _Pernyi_ worm is much more easily reared than that of _Yamamai_,
but still great care is needed; fresh food of course is essential, and
a slight sprinkling of the branches and worms in very warm weather is
advisable; although it is not so necessary as with _Yamamai_. It is
remarkable that _Pernyi_ worms, fed in the open air, on oak trees,
do not, at present, thrive so well as those fed in-doors, but this,
doubtless, is a question of acclimation. I advise white oak (_Quercus
alba_) as food, if it can be readily obtained, but failing that, pin
oak (_Quercus palustris_) will do; and I have no doubt that they will
feed on any kind of oak. They will, indeed, feed on birch, and on
sweet gum (_Liquidambar_), but oak is the proper food. It is worthy of
remark that _Pernyi_ bears a strong resemblance to our _Polyphemus_,
but it is more easily reared in confinement, and double brooded; an
important fact for the silk culturist. From American reared eggs, I
obtained cocoons as early as July 4th, the perfect insect emerging on
July 31. Copulation immediately ensued, and the resulting eggs hatched
only on August 12, ten days only from the time of laying; and as the
worm feeds up in about four or five weeks, this affords plenty of
time for rearing the second brood. It must be remembered that on the
quantity and quality of food, much depends, not only with _Pernyi_
but with all caterpillars. By furnishing food sparingly the time of
feeding would be much prolonged.

I have already said that both _Yamamai_ and _Pernyi_ should be fed
under shelter for the reasons given, but there is another reason of
less importance. The young worms are liable to be attacked by spiders
and wasps, and even after the second month, they are not safe from
these enemies. I have seen a wasp bite a large caterpillar in two,
carry off the anterior section and return for the posterior, which
had held on by its prolegs. Did the wasp anticipate this fact, and
therefore carry off the anterior part first? As to the spiders, they
form a series of pulleys and hoist the caterpillar off its legs,
sucking its juices at leisure.

And now I must devote a few words to the advisability of silk culture
from a pecuniary point of view. _Bombyx mori_, or the ordinary
mulberry silkworm, is, of course, the best to rear, if you can obtain
healthy eggs. But this is the difficulty, and thence arises the
necessity of cultivating other silk-producing species. I imagine
that silk can be produced in most of the States of the Union, and
manufactured from the cocoon at a large profit; but for the present,
we will leave the manufacture out of the question, and consider only,
whether it will not pay to rear eggs and cocoons for sale? It must
be remembered that European manufacturers are at this moment largely
dependent on foreign countries for the supply of both eggs and
cocoons; and this, because of the general prevalence of disease among
all the races of _Bombyx mori_. And now, to what extent does the
reader suppose this dependence exists? Of cocoons I have no returns at
hand, but, of raw silk, European manufacturers purchase, annually, not
less than $160,000,000 worth; and of eggs (_Bombyx mori_) to the
value of $10,000,000. This, then, is a business of no trifling amount.
California seems to be alive to the fact, and, I am informed, raised,
this last season, $3,000,000 cocoons; and, for sale, about 4,000
ounces of eggs, worth at least $4 per ounce, wholesale. Now, there is
no earthly reason why California should monopolize this business.
Why are not companies formed in other States for this purpose? or if
private individuals lack the enterprise or the means, why do not the
legislatures, of those States most favorably located, do something by
way of starting the business? A few thousand dollars loaned, or even
donated, may prove to be a valuable investment for the people at
large, and, even supposing a failure, would not be a very great loss
to any body.

So far as farmers are concerned, it may interest them to know that one
man in England, Capt. Mason, clears $50 per acre by rearing silkworms
(_Bombyx mori_ in this case), and I much doubt whether any crop raised
here pays as well.

By way of commencement, then, let everybody that has sufficient
leisure set to work, and rear as many silkworms, of the above-named
species, as he possibly can; and if the process be not remunerative in
a pecuniary sense, it most assuredly will be in the amount of pleasure
and knowledge obtained.

One caution I must give to those who cultivate _Bombyx mori_. Although
_Yamamai_ requires sprinkled branches, _Bombyx mori_ does not; nor
must the leaves be furnished to them while wet with rain or dew.

       *       *       *       *       *


EFFECT OF COLD UPON IRON.--The article upon this subject, giving
experiments of Fairbairn and others, referred to in our editorial
upon the same subject, in our last issue, was crowded out by press of
matter. The reader will find it in the present number.

       *       *       *       *       *




UNIVERSAL BORING MACHINE.


Our readers will recollect an illustrated description of an universal
wood-working machine, published on page 79, Vol. XIII. of the
SCIENTIFIC AMERICAN. The machine herewith illustrated is manufactured
by the same firm, and is a valuable addition to the many excellent
wood-working machines now in use. A boring machine, though one of the
simplest, is by no means an unimportant adjunct to a full outfit of
wood-working machines. The one shown in our engraving is one of the
most complete ever brought to our notice, and the great variety of
work it is capable of performing, renders the name chosen for it
peculiarly applicable. It is called the "Universal Boring Machine"
because the most prominent feature of its construction is its power to
bore a hole in any desired angle with the axis of the bit.

Any sized bit required is inserted into the chuck, which is adjustable
to fit large and small shanks. The mandrel which carries the chuck is
made to traverse by a foot lever, so as to bore any depth up to twelve
inches. The mandrel is driven by belt from a cone pulley of three
faces, which gives the proper speeds for different sized bits.

Slots and stops upon the table enable the work to be set at any
desired angle on the horizontal plane, while the table can be set on
an incline to any angle not exceeding forty-five degrees. The table
is twenty-one inches wide, with fifteen inches slide, and it can be
raised or lowered fifteen inches.

The countershaft rests in self-adjusting boxes, and has a tight and
a loose pulley eight inches in diameter. The traversing mandrel is of
the best quality of steel, and the machine is otherwise made of iron
in a substantial manner.

[Illustration: McBETH, BENTEL, & MARGEDANT'S UNIVERSAL BORING
MACHINE.]

The several adjustments enable the operator to do all kinds of light
and heavy boring, with ease and with great rapidity.

This machine was awarded the first premium at the Cincinnati
Industrial Exposition, in October, 1870, and was patented through the
Scientific American Patent Agency, Aug. 16, 1870. It is manufactured
by McBeth, Bentel and Margedant, of Hamilton, Ohio, whom address for
machines rights to manufacture, or other information.

       *       *       *       *       *




COMBINED TRUNK AND ROCKING CHAIR.


A unique invention, calculated to increase the comforts of travellers
on steamboats, ships, and in crowded rooms of hotels, is illustrated
in the engraving published herewith. It is the invention of T. Nye,
of Westbrook, Me., and was patented by him, June 18, 1867. It is a
combined trunk and rocking chair. The rockers are made to fold into
recesses, where they are retained by suitable appliances till wanted.
The trunk being opened, as shown, forms a back to the seat, which
is held by metallic braces. When closed, the whole presents the
appearance of an ordinary trunk.

[Illustration]

       *       *       *       *       *




COSMETICS.


The extensive use of preparations for hiding nature's bloom on the
human countenance, and presenting to our view a sort of metallic
plaster, suggests the inquiry, "how are these pigments made?" Without
going into an unnecessary analysis of the "Bloom of Youth," the
"Rejuvenator," the "Corpse Decorator," or the other inventions for
destroying the skin, with which the druggists' stores abound, we
may state again the fact, always unheeded, that all the detestable
compounds are injurious. They are nearly all metallic poisons, and,
if there be any that are innocent of this charge, they are in every
instance harmful to the health. The color and surface of the skin
cannot be changed by any application which does not close the pores;
the pores, which are so exquisitely fine that there are millions of
them to the square inch, and which must be kept open if a healthy and
cleanly body is to be preserved. There is more breathing done through
the pores of a healthy person than through the lungs; and we need not
remind our readers of a ghastly piece of cruelty once enacted in Paris
(that of gilding the body of a child, for a triumphal procession,
which killed the subject in two hours), to show that the stoppage, in
any degree, of the natural functions of so important an organ as the
skin, is injurious. The immediate effect of the use of such compounds
is to destroy the vitality of the skin, and to render it, in
appearance, a piece of shriveled parchment. We must warn our readers
that a temporary and meretricious "bloom" can only be attained at the
cost of future freshness and lively appearance, so that a year or two
of "looking like paint" is followed by a long period of "looking like
dilapidation."

       *       *       *       *       *




SMITH'S INFANT DINING CHAIR.


The accompanying engraving illustrates a convenient and cheap infant
dining chair, which can be attached to any of the ordinary chairs in
common use.

[Illustration]

It consists of a chair without legs, suspended by the posts of the
back, as shown, on pins engaging with hooked bars, which are placed
upon the back of an ordinary chair. The details of the device will be
seen by a glance at the engraving. The chair is adjusted in hight
by placing the pins in the proper holes in the posts made for this
purpose.

For further information, address Smith, Hollenbeck & Co., Toledo,
Ohio.

       *       *       *       *       *




THE MEDICINES OF THE ANCIENTS.


At the recent commencement of the Homeopathic College in this city,
Mr. S. H. Wales, of the SCIENTIFIC AMERICAN addressed the graduating
class, and from his remarks, we quote the following:

"Many writers of our time persist in regarding this, above all others,
as the best period in the history of our race; and, doubtless, it is
true in many important respects. But I cannot forbear the suggestion
at this moment that there was a time in the history of the world
when the science of medicine was unknown, when people lived to the
incredible age of many centuries; and, even after the span of life
had been reduced to threescore and ten, sickness was comparatively
unknown. In ancient times, it was looked upon as a calamity, that
had overtaken a tribe or people, when one of its members prematurely
sickened and died.

"Other arts and sciences flourished in Rome long before medicine
was thought of; and the historian tells us that the first doctor who
settled in Rome, some two hundred years before Christ, was banished on
account of his poor success and the very severe treatment applied to
his patients; and it was a hundred years before the next one came. He
rose to great popularity, simply because he allowed his patients to
drink all the wine they wanted, and to eat their favorite dishes.
Some writer on hygiene has made the statement that the whole code
of medical ethics presented by Moses consisted simply in bathing,
purification, and diet. This simplicity of life was not confined to
the wandering tribes who settled in the land of Canaan, but was the
universal custom of all nations of which history gives us any account.
This simple arrangement for health was considered enough in those
primitive times, when the human system had not been worn out and
exhausted by depletive medicines. The luxuries of public baths,
athletic sports and games were deemed ample, both to educate the
physical perceptions and to prevent disease.

"All this wisdom, which had its origin in ancient games and sports
of the field, led to the erection of extensive bath-houses, and the
adoption of other healthful luxuries to which all the people could
resort to recreate their wasted powers."

       *       *       *       *       *




BARNES' VENTILATOR FOR MATTRESSES, ETC.


Many diseases are caused by the use of beds not properly aired; and
it is difficult, if not impossible, to properly air, or ventilate,
a mattress, made in the usual manner. If this could be done more
thoroughly than it generally is, much sickness would be avoided.

[Illustration]

To secure this object cheaply and efficiently is the design of the
invention herewith illustrated. By it a complete circulation of
air through the mattress is secured, which carries off all dampness
arising from constant use. Thus the mattress becomes more healthy for
sleeping purposes, more durable and better fitted for the sick room.
The ventilators consist of coiled wire, covered with coarse cloth
(to prevent the stuffing closing up the tube), running through the
mattress in all directions. The ends of the coils are secured to the
ticking by means of metal thimbles, inside of which are pieces of wire
gauze, to prevent insects getting in, but which admit air freely. The
cost of the ventilators is small, and they will last as long as any
mattress. They can be applied to any bed at small expense.

This invention was patented through the Scientific American Patent
Agency, January 10, 1871. The right to manufacture will be disposed
of in any part of the country. Further information can be obtained by
addressing the proprietors, Barnes & Allen, Hoosick Falls, N. Y.

       *       *       *       *       *


The third annual exhibition of the National Photographic Association
takes place at Horticultural Hall, Philadelphia, June 6, 1871. Prof.
Morton is to deliver two lectures on Light.

       *       *       *       *       *




A SCIENTIFIC AND TECHNICAL AWAKENING.


Our English cotemporary, _Engineering_, appears to have seriously
exercised itself in the perusal of our good-natured article
on "English and American Scientific and Mechanical Engineering
Journalism," which appeared in the SCIENTIFIC AMERICAN, February
4th; at least, we so judge from the tenor of an article in response
thereto, covering a full page of that journal. The article in question
is a curiosity in literature. It deserves a much wider circulation
than _Engineering_ can give it, and we would gladly transfer it to our
columns, but for its exceeding length--a serious fault generally, not
only with _Engineering's_ articles, but most other technical journals
published in England. It would scarcely do for them to be brief in
their discussions, and above all other things, spice and piquancy
must always be excluded. _Engineering_ evidently labors under the
conviction that the heavier it can make its discussions, the more
profoundly will it be able to impress its readers. Hence, we are
equally astonished and gratified to find a gleam of humor flashing out
from the ordinary sober-sided composition of our learned contemporary.
The article came to us just as we were laboring under an attack of
dyspepsia, and its reading fairly shook our atrabilious _corpus_. We
said to ourselves, "can it be possible that _Engineering_ is about to
experience the new birth, to undergo regeneration, and a baptism of
fire?" The article is really worth reading, and we begin to indulge
the hope that at least one English technical is going to try to make
itself not only useful, but readable and interesting. And what is
most perplexingly novel in this new manifestation, is the display of
a considerable amount of egotism, which we had always supposed to be
a sinful and naughty thing in technical journalism. And, as if to
magnify this self-complaisance, it actually alludes to its "_own
extensive and ever-increasing circulation in America_." Now to show
how small a thing can impart comfort to the soul of our cotemporary,
we venture to say that the circulation of _Engineering_ in this
country cannot much exceed three hundred copies per week.

It evidently amazes our English cotemporary that a journal like the
SCIENTIFIC AMERICAN, which, according to its own notions, is chiefly
the work of "scissors and paste," should circulate so widely; and it
even belittles our weekly circulation by several thousand copies,
in order to give point to its very amusing, and, we will also add,
generally just criticism.

The writer in _Engineering_, whoever he may be, appears to be a sort
of literary Rip Van Winkle, just waking out of a long sleep; and
he cannot get the idea through his head that it is possible that a
technical journal can become a vehicle of popular information to
the mass of mankind, instead of being the organ of a small clique of
professional engineers or wealthy manufacturers, such as seems to
hold control of the columns of _Engineering_, and who use it either
to ventilate their own pet schemes and theories, or to advertise, by
illustration and otherwise, in the reading columns, a repetition of
lathes, axle-boxes brakes, cars, and other trade specialities, which
can lay little or no claim to novelty. It is, furthermore, a crying
sin in the estimation of our English critic that American technical
journals do not separate their advertisements from the subject matter;
and he thinks that when Yankee editors learn that trade announcements
are out of place in the body of a journal, they will see how to make
their journals pay by making them higher priced. Now we venture to
say, without intending to give offence, that Yankee editors understand
their business quite as well as do English editors; and it is
presumable, at least, that they know what suits their readers on
this side, much better than do English editors. We venture to
suggest--modestly, of course--that journalism in the two countries
is not the same, and should the editor of _Engineering_ undertake
to transfer his system of intellectual labor to this side of the
Atlantic, he would not be long in making the discovery that those
wandering Bohemian engineers, who, he tells us, are in sorrow and
heaviness over the short-comings of American technical journals, would
turn out after all to be slender props for him to lean upon. We think
it probable, however, that with a little more snap, a journal like
_Engineering_ might possibly attain a circulation, in this country, of
500 or 1000 copies weekly.

Why, American engineers have scarcely yet been able to organize
themselves into an association for mutual advancement in their
profession, much less to give the reading public the benefit of their
experience and labors! This fact alone ought, of itself, to satisfy
_Engineering_ that no such journal could profitably exist in this
country. Whenever our American engineers are ready to support such a
journal, there will be no difficulty in finding a publisher.

_Engineering_, in its casual reference to the various technical
journals of America, omits to name our leading scientific monthly, but
introduces with just commendation a venerable cotemporary, now upwards
of three score years of age. Now, it is no disparagement of this
really modest monthly to say, that perhaps there are not sixty hundred
people in the States who know it, even by name; and so far as the use
of "scissors and paste" are made available in our technical journals,
we venture the assertion that the editorial staff expenses of the
SCIENTIFIC AMERICAN are as great, if not greater, than those of
_Engineering_. The question, however, is not so much one of original
outlay, but which of the two journals gives most for the money. In
this very essential particular, and with no intention to depreciate
the value of _Engineering_, we assert, with becoming modesty, that the
SCIENTIFIC AMERICAN occupies a position which _Engineering_ will never
be able to attain.

       *       *       *       *       *




THE SHERMAN PROCESS.


When people boast of extraordinary successes in processes the details
of which are kept profoundly hidden from public scrutiny, and when the
evidences of success are presented in the doubtful form of specimens
which the public has no means of tracing directly to the process, the
public is apt to be skeptical, and to express skepticism often in not
very complimentary terms.

For a considerable time, the public has been treated to highly-colored
accounts of a wonderful metallurgic process whereby the best iron and
steel were said to be made, from the very worst materials, almost
in the twinkling of an eye. This process has been called after its
assumed inventor, or discoverer, the "Sherman Process." The details of
the process are still withheld, but we last week gave an extract from
an English contemporary, which throws a little light upon the subject.

The agent relied upon to effect the remarkable transformation claimed,
is iodine, used preferably in the form of iodide of potassium, and
very little of it is said to produce a most marvellous change in the
character of the metal.

A very feeble attempt at explaining the rationale of this effect has
been made, in one or two English journals, which we opine will not
prove very satisfactory to chemists and scientific metallurgists. The
_Engineer_ has published two three-column articles upon the subject,
the first containing very little information, and the second a great
number of unnecessary paragraphs, but which gives the proportion of
the iodide used, in the extremely scientific and accurate formula
expressed in the terms "a small quantity."

Assertions of remarkable success have also been given. Nothing,
however, was said of remarkable failures, of which there have
doubtless been some. A series of continued successes would, we
should think, by this time, have sufficed for the parturition of
this metallurgic process, and the discovery would ere this have been
introduced to the world, had there not been some drawbacks.

We are not prepared to deny _in toto_ that the process is all that is
claimed for it; but the way in which it has been managed is certainly
one not likely to encourage faith in it.

The very name of "process" implies a system perfected, and if it be
still so far back in the experimental stage that nothing definite in
the way of results can be relied upon, it is not yet a process. If, in
the use of iodine, in some instances, fine grades of iron or steel are
produced, and in as many other experiments, with the same material,
failures result, it is just as fair to attribute the failures to the
iodine, as the successes. A process worthy the name is one that acts
with approximate uniformity, and when, in its use, results vary
widely from what is usual, the variation may be traced to important
differences in the conditions of its application.

On the whole, we are inclined to believe Mr. Sherman's experiments
have not yet developed a definite process, and we shall receive with
much allowance the glowing statements published in regard to it, until
such time as it can face the world and defy unbelief.

The patents obtained by Mr. Sherman seem to cover the use of iodine,
rather than the manner of using it, and throw no light upon the
rationale of the process.

A patent was granted by the United States Patent Office, Sept. 13,
1870, to J. C. Atwood, in which the inventor claims the use of iodide
of potassium in connection with the carbons and fluxes used in making
and refining iron. In his specification he states that he uses about
_fifteen grains_ of this salt to eighty pounds of the metal. This
is about 1/373 of one per cent. He uses in connection with this
exceedingly small proportion of iodide of potassium, about two ounces
of lampblack, or charcoal, and four ounces of manganese, and asserts
that steel made with these materials will be superior in quality
to that made by the old method. These claims we are inclined to
discredit. Certainly, we see no chemical reason why this small amount
of iodide should produce such an effect, and the specification itself
throws no light upon our darkness.

If the experiments in these so-called processes have no better basis
than is apparent from such information as at present can be gathered
respecting them, it is probable we shall wait some time before the
promised revolution in iron and steel manufacture is accomplished
through their use.

       *       *       *       *       *




RUBBER TIRES FOR TRACTION ENGINES.


When it was first discovered that a smooth-faced driving wheel,
running on a smooth-faced rail, would "bite," the era of iron railways
and locomotive engines may be said to have fairly commenced. The
correction of a single radical error was, in this case, the dawn of a
new system of travel, so extensive in its growth and marvelous in its
results, that even the wildest dreamer could not, at that time, have
imagined the consequences of so simple a discovery.

A popular and somewhat similar error regarding the bite of wheels on
rough and uneven surfaces, has also prevailed. We say popular error,
because engineers have not shared it, and it has obtained, to any
notable extent, only among those unfamiliar with mechanical science.
The error in question is, that hard-surfaced wheels will not bite on
a moderately rough surface, sufficiently to give an efficient tractile
power. It seems strange that this error should have diffused itself
very extensively, when it is remembered that a certain degree of
roughness is essential to frictional resistance. The smoothness of the
ordinary railway track is roughness compared to that of an oiled or
unctuous metallic surface; and it has been amply demonstrated that
the resistance of friction, of two bearing surfaces depends, not
upon their extent, but upon the pressure with which they are forced
together. A traction wheel, of given weight, resting upon two square
inches of hard earth or rock, would develop the same tractile power
as though it had a bearing surface of two square feet of similar
material.

On very rough and stony ways, however, another element practically of
no importance on moderately rough ways, like a macadam surface or a
concrete road, where the prominences are nearly of uniform hight, and
so near together as to admit between their summits only very small
arcs of the circumference of the wheel; comes into action. This
element is the constantly recurring lifting of the superincumbent
weight of the machine. Even this would not result in loss of power,
could the power developed in falling be wholly applied to useful work
in the direction of the advance of the engine. The fact is, however,
that it is not so applied, and in any method of propulsion at present
known to engineering science, cannot be so applied. Above a certain
point where friction enough is developed to prevent slip, the more
uneven the road surface is, the greater the power demanded for the
propulsion of the locomotive. And this will hold good for both hard
and soft-tired wheels.

What then is the advantage, if any, of rubber-tired wheels? The
advantages claimed may be enumerated as follows: increased tractile
power, with a given weight, secured without damage to roadways; ease
of carriage to the supported machinery, whereby it--the machinery--is
saved from stress and wear; and economy of the power, expended in
moving the extra weight required by rigid-tired wheels, to secure the
required frictional resistance. The last-mentioned claim depends upon
the first, and must stand or fall with it. The saving of roadway,
ease of carriage, and its favorable result upon the machinery, are
generally conceded.

A denial of the first claim has been made, by those interested in the
manufacture of rigid-tired traction engines and others, in so far
as the rubber tires are employed on comparatively smooth surfaces;
although the increased tractile power on quite _rough_ pavements and
roads is acknowledged.

This denial is based upon results of experiments performed on the
streets of Rochester, England, between the 9th October and the 2nd
November, 1870, by a committee of the Royal Engineers (British Army),
with a view to determine accurately the point in question.

Care was taken to make the circumstances, under which the trials
took place, exactly alike for both the rubber and the iron tires. The
experiments were performed with an Aveling and Porter six-horse power
road engine, built in the Royal Engineers' establishment. The weight
of the engine, without rubber tires, was 11,225 pounds; with rubber
tires, it weighed 12,025 pounds. Without rubber tires it drew 2.813
times its own weight up a gradient of 1 in 11; with rubber
tires, it drew up the same incline 2.763 times the weight of engine,
with the weight of rubber tires added; showing that, although it drew
a little over 2,200 pounds more than it could do without the rubber
tires, the increase of traction was only that which might be expected
from the additional weight.

It is claimed, moreover, that the additional traction power and
superior ease of carriage on rough roads, secured with rubber tires,
is dearly bought at the very great increase in cost, of an engine
fitted with them, over one not so fitted.

This is a point we regard as not fully settled, though it will not
long remain in doubt. There are enough of both types of wheels now in
use to soon answer practically any question there may be of durability
(upon which the point of economy hinges), so far as the interest on
the increased cost due to rubber tires, is offset against the greater
wear and tear of iron rimmed wheels. It is stated, on good authority
that a rubber tired engine, started at work in Aberdeen, Scotland,
wore out its tires between April and September, inclusive, and when
it is taken into consideration, that the cost of these tires is
about half that of other engines, made with solid iron rimmed driving
wheels, it will be seen that, unless very much greater durability than
this can be shown for the rubber, the advantages of such tires are
very nearly, if not more than, balanced by their disadvantages.

The fact that one set of tires wore out so soon does not prove a rule.
There may have been causes at work which do not affect such tires
generally, and it would be, we think, quite premature to form
favorable or unfavorable judgment, of relative economy from such data
as have been yet furnished.

The difference in the current expenses of running the two most
prominent types of engines, with hard and soft tires, now in use, does
not affect the question of rubber tires, unless it can be shown that
these tires necessitate, _per se_, such a form of engine as requires
a greater consumption of fuel, and greater cost of attendance, to
perform a given amount of work.

       *       *       *       *       *




CENTRAL SHAFT OF THE HOOSAC TUNNEL.


As many of our readers have evinced much interest and ingenuity on
the question of the propriety of placing reliance upon the accuracy of
dropping a perpendicular from the top to the bottom of a shaft 1,030
feet in depth, by means of an ordinary plummet, we take the earliest
opportunity of settling the matter beyond dispute, by reporting
the results lately obtained, through a series of experiments by the
engineers in charge, for the ultimate purpose of laying down the
correct line for the tunnel.

The perpendicular line has, of course, been dropped many times, and
the main result taken. The plummet used is made of steel, properly
balanced and polished, in shape something like a pineapple, and of
about the same size, weighing fifteen pounds. It was suspended, with
the large end downwards, by a thin copper wire, one fortieth of an
inch in diameter, immersed in water; and, after careful steadying with
the hand, occupied about an hour in assuming its final position or
motion, which, contrary to the expectation and theories of many,
resulted in a circular motion around a fixed point, the diameter of
the circle being a mean of one quarter of an inch. The suspending
wire in these operations was not quite the entire length of the shaft,
being only 900 feet; and before the plummet had settled, the wire had
stretched nearly twenty feet.

The suspension of the plummet in water was not considered necessary
for any other reason than that water was continually trickling down
the wire, and dropping on the plummet. The experiments so far have
not been of the perfect character it is determined to attain, when the
final alignment is made, as, until the headings east and west of the
shaft have advanced to a considerable distance, any slight error would
be of no account.

A neat and ingenious instrument has been constructed for determini