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[Illustration: ARMY AIRPLANE GLIDING TO NORTH ISLAND OVER U. S. CRUISER
“SAN DIEGO”]


THE AVIATOR AND THE WEATHER BUREAU

by

FORD A. CARPENTER, LL.D.

Meteorologist

Illustrated with Photographs and Charts
by the Author and Others






Published by the
San Diego Chamber of Commerce
1917

Published by permission
Dated August 25, 1916

Second edition, 5,000 copies

J. Horace McFarland Company
Mt. Pleasant Press
Harrisburg, Pennsylvania




Introductory Note


This is a brief but general account of the history of aviation as
it is associated with southern California, a description of the War
Department school of aviation at San Diego, a syllabus of the course
of lectures delivered there on the subject of practical meteorology as
applied to aviation, a narrative of weather-study from an airplane, and
a recital of subsequent active coöperation between the aviators and the
U. S. Weather Bureau.[A]

    [A] It may be remembered that the weather service of the
        United States originated with the Signal Corps of the Army
        and that the Weather Bureau was created from it by Act
        of Congress, June, 1891, and made a bureau of the U. S.
        Department of Agriculture. As a former member of the Signal
        Corps the writer enjoyed the renewal of old friendships
        among the officers at the Aviation School. Col. W. A.
        Glassford, Signal Corps, U. S. Army, Commandant of the War
        Department Aviation School at San Diego, kindly read the
        manuscript of the following pages and the writer gratefully
        acknowledges his valuable suggestions.

Much of the material in the following pages was obtained by the writer
while detailed as Lecturer in Meteorology to the Signal Corps, War
Department Aviation School at San Diego, in 1915–1916, also when
detailed in the same official capacity to the U. S. Army Military
Training Encampment, Monterey, 1916; and at the summer sessions of the
University of California during 1914–1916.

  LOS ANGELES, CAL.,
   February, 1917.




     _To_
  _J. S. A._




Table of Contents


  CHAPTER I

  The Signal Corps Aviation School at San Diego, California            7


  CHAPTER II

  Applied Meteorology for the Aviator                                 11


  CHAPTER III

  Weather Observations from an Airplane                               16


  CHAPTER IV

  Investigating the Upper Air                                         25




List of Plates


  Figure
   No.                                                              Page
      Army airplane gliding to North Island Over U. S. Cruiser
          “San Diego”                                _Frontispiece_

   1. Congressional Medal awarded Wright brothers                     33

   2. Ascent of sounding balloons at Avalon                           34

   3. Meteorograph which made the ascent of July 27, 1913             35

   4. First flight of airplane carrying two persons                   36

   5. Sub-station at Mount Wilson Observatory                         37

   6. Type of airplane used in 1911 on North Island                   38

   7. Discussing a flight                                             39

   8. Captain Culver and parachute for determining wind-direction     40

   9. Lieutenant Gorrell, U. S. Infantry, as observer                 41

  10. Point Loma from the eastern shore of North Island               42

  11. San Diego, across Spanish Bight, from U. S. Aviation School,
        at twilight                                                   43

  12. Instructor Brindley and Meteorologist Carpenter in
        Military Tractor No. 50                                       44

  13. Military Tractor No. 50                                         45

  14. “Trimming” Tractor No. 50                                       46

  15. Military Tractor No. 50 just before leaving the ground          47

  16. San Diego harbor at over two thousand feet altitude             48

  17. San Diego viewed from an altitude of thirty-five hundred
        feet                                                          49

  18. Military Tractor No. 50 viewed from the ground                  50

  19. Flying Squad’s Wind Direction Pennant Tower                     51

  20. The Aviation School Motor-Boat “Pronto”                         52

  21. U. S. Aviation Field at three thousand feet altitude            53

  22. Repair Shop, U. S. Aviation School, San Diego, Cal.             54




The Aviator and the Weather Bureau




CHAPTER I

THE SIGNAL CORPS AVIATION SCHOOL AT SAN DIEGO


_History._--The year 1911 marked the beginning of the United States
aviation school at San Diego. There is no finer tribute to the
equability and general excellence of the climate of southern California
than that given in the history of aëronautics. It was here, in 1900,
that Chanute completed his early and epoch-making observations of the
flight of gulls and pelicans. These contributed largely to the success
of the Wright brothers a few years afterward. It was in southern
California, six years ago, that Harkness, in an Antoinette, made his
record monoplane flight to Tia Juana. San Diego witnessed the flying
of the first seaplane, by Curtiss, five years ago. It is in this
district that not only the War Department aviation school and a number
of commercial flying schools are located, but also one of the large
airplane[B] factories in this country.

    [B] The National Advisory Committee for Aëronautics in
        its report of October 17, 1916, on Nomenclature for
        Aëronautics, the name _airplane_ is substituted for “Any
        form of aircraft heavier than air which has wing surfaces
        for sustention, with stabilizing surfaces, rudders for
        steering, and power-plant for propulsion through the air.”

_Location of the School._--Whatever the final action may be as to
permanent location, it has been conceded by all authorities that
the situation of the aviation school on North Island, San Diego Bay,
is ideal. (See Fig. 21.) The so-called island is connected with the
peninsula of Coronado by a narrow sand-spit, and it comprises many
hundred acres of level land free from buildings and any sort of
overhead wires. The island fronts the ocean on the south; Point Loma on
the west with the narrow entrance to the bay between; to the north is
the city of San Diego across the bay; and Coronado just beyond Spanish
Bight on the east. This natural arrangement gives good air conditions
for beginners, and also enables them to use the smooth waters of the
bay as well as the rough ocean water for the seaplanes. The proximity
of this location to San Diego is also a distinct advantage. (See Fig.
11.) All of the structures of the aviation school on North Island are
temporary, the buildings consisting of a scattering array of huge sheds.

_Character of Instruction._--Officers from all branches of the army
volunteer for this service. The qualifications of an aviator are
caution, judgment, and technical skill. Deficiencies in caution and
judgment being temperamental are rarely remedied, while technical
skill is largely a matter of acquirement. Less than ninety days are
allowed for qualification as a junior aviator, and if in that period
the officer’s deficiencies are found to be inherent, he returns to his
company.

The school is a place for hard work and quick thinking. Detail in the
repair shop is part of the course, as is also the use of the gasoline
engine in motor trucks as well as in aircraft. (See Fig. 22.) Theory
and practice are closely united: the former is carried on by means
of bi-daily lectures, while the early morning hours are devoted to
flying. Pilot-and-observer machines equipped with double control are
used in instruction. The aviation instructor ascends with the student
and allows him to manipulate the controls, only resuming the management
of the airplane in an emergency. Needless to say, the life of an
instructor is a most hazardous one and full of thrills. His duty is to
be on the alert to correct errors in the manipulation of the machine.
After every trip the instructor reviews, point by point, the features
of the flight, showing the pupil his deficiencies and explaining how
he may avoid them in the future. The instruction is terse but kindly,
and the manner of imparting this information leaves nothing to the
imagination. After watching student and instructor, and closely
studying the finished work of an aviator, it is my opinion that in no
other occupation must there be such perfect coördination between mind
and muscle: the perfectly qualified aviator is the modern super-man.[C]

    [C] The army aviator of today is picked for his quickness of
        mind and body, and the first thing that strikes you about
        him is a sort of feline, wound-up-spring alertness. Then
        you note his reticence, the cool reserve of a man whose
        lot is to express himself in deeds rather than words. And,
        lastly, there is the quiet seriousness, verging almost
        on sadness, of a man who must hold himself ready to look
        death between the eyes at any moment and yet keep his
        mind detached for other things.--Lewis R. Freeman in the
        _Atlantic Monthly_.

_Results of a Year’s Work._--During the year 1915, the students of the
aviation school made 3,652 flights with a total time aloft of 1,516
hours, and a mileage of 95,000. As regards weather conditions affecting
flights, it will be found interesting to note Chart No. 5 giving
number of flights and duration for the fourteen months ending August,
1916, which shows that work progressed regardless of weather, and at
an increasing rate.[D] In February, a military tractor-seaplane (an
all-California product), 125-horsepower motor, with twenty-six gallons
of gasoline, four gallons of oil, and three passengers, making a total
weight of 3,100 pounds, reached an altitude of 12,362 feet. This was
the world’s record, the previous altitude under the same conditions
having been 9,000 feet.

    [D] “It is estimated that the average cost to France of
        training each pilot is five thousand dollars ... no less
        than from four to six months are devoted to the training
        of finished pilots. Although I have just come from France,
        the progress of aviation is so rapid that much of my own
        knowledge may be out of date before I again return to the
        front.”--C. D. Winslow, “With the French Flying Corps,”
        1917, 4–5: N. Y.




CHAPTER II

APPLIED METEOROLOGY FOR THE AVIATOR


_Activities of the Weather Bureau in Relation to
Aëronautics._--Naturally the progress of aërial navigation has at all
times been rather closely connected with the Weather Bureau. For over
a decade the Bureau has not been content with surface observations
but has maintained laboratories for the study of the upper air. The
results of its observations are considered a mine of information for
the student aviator. Prof. Charles F. Marvin, the Chief of the Weather
Bureau, is a member of the National Advisory Committee for Aëronautics,
and chairman of a subcommittee engaged on the determination of the
problems of the atmosphere in relation to aëronautics.[E]

    [E] Monthly Weather Review, 1915, 32:500. Washington.

The first official coöperation between the Weather Bureau and the War
Department aviation school was inaugurated in the year 1914 by Dr.
W. J. Humphreys, Professor of Meteorological Physics, when he was
detailed to give a course of lectures. It was during this course that
he lectured on “Holes in the Air.”[F] This paper has been reprinted as
a textbook for the aviation school.

    [F] Popular Science Monthly, 1914, 44:18–34, N. Y.

_Early Studies in Aëronautics._--Unofficially, however, the coöperation
extended back some fifteen years prior to that time, when the writer
was in charge of the local office of the Weather Bureau at San Diego,
and assisted the aëronautical engineer, Octave Chanute, in his
observations and experiments on San Diego Bay.[G] At this time hundreds
of photographs of sea-gulls, pelicans, and other soaring birds were
made, and both birds and photographs studied and analyzed. Ever since
then more or less interest has been taken by the writer in aërial
navigation. During an assignment to the Central Office the work of
the Wright brothers was observed and studied. The association with
the late Octave Chanute and his friends, the Wrights, during their
experimental flights at Fort Meyer, Virginia, in September, 1908, is
counted among the many pleasant memories of the Washington visit. It
was here that was witnessed the first flight with a passenger (see Fig.
4), Mr. Orville Wright taking up with him Major (now Colonel) George O.
Squier, the present head of the aviation branch of the army. Such was
the infancy of the flying-machine that at that date no fatalities had
occurred. A few years later the writer had the pleasure of accompanying
Mr. Glenn Curtiss while he was determining a site for his school, which
was finally located on North Island. (See Fig. 6.) Shortly afterward,
from this place, Harry Harkness made record amateur cross-country
flights in an Antoinette monoplane.

    [G] “Climate and Weather of San Diego,” Carpenter, 1913, 57–59,
        San Diego.

_Active Work of the Weather Bureau._--During the score of years that
the writer has been in charge of the San Diego and Los Angeles stations
of the Weather Bureau, interest in flying has been cumulative. Efforts
have been made to furnish aviators with available data so that at the
present time a day seldom passes without conference With officials or
students of Government or private flying schools in this vicinity.

_Lectures on Meteorology as Applied to Aviation._--Through the War
Department, October, 1915, on request of the commanding officer of the
Signal Corps aviation school, at San Diego, the writer was directed by
the Chief of the Weather Bureau to deliver two lectures of which the
following are outlines:


“_What the Weather Bureau Offers the Aviator_”

(Illustrated by 37 lantern-slides from photographs by the author)

  Introductory:
    Weather service once part of the Signal Corps, U.S.A.
    Transfer in 1891 to the Department of Agriculture.

  Distribution of weather stations in the United States:
    Character of data obtainable:
      Advance data from the daily map such as
        Position of high and low areas.
      Weather conditions from sub-stations in vicinity.

  The weather map:
    How constructed.
    How distributed.
    Specimen maps showing differing conditions in California.
      Winds, velocity and frequency:
        On-shore.
        Off-shore.
      Discussion of air conditions December 20–22, 1914.
    The international weather map.
      Relation to weekly forecasts.

  Cardinal climatic features:
    Ascending winds and types producing them:
      Cloud, fog, precipitation.
    Descending winds:
      “Northers” and dust-storms.
      Thermograph and hygrograph traces.

  Factors in the meteorology of southern California:
    Influence of latitude:
      Sea.
      Mountains.
      Desert.
    Path and distribution of storm areas.
    Knowledge of local climatology necessary in flying.
    Local winds discussed:
      “Woollies” (descending wind eddies).
      “Chubascos” (south coast thunder squall).
      “Santa Anas” (northeasterly and desiccating).
      “Wilmingtons” (northwesterly line-squall).


“_Practical Meteorology for the Aviator_”

(Illustrated by 72 lantern-slides from photographs by the author)

  Historical:
    Original work begun in Scotland, year 1749.
    Characteristics--
      English work; Dines’ minute meteorograph.
      French work; Dr. Berson’s balloon ascent of 6½ miles.
      German work; detailed data in low altitudes.
      American work began with Franklin.
  The Upper Air:
    Definition:
      “Stratosphere” is (according to some authorities) the
        dynamical laboratory of the atmosphere where the
        main causes of pressure originate.
    Results in America:
      Balloon meteorograph (Fig. 3).
      Charts showing rate of increase in wind velocity with
        elevation (Chart No. 4).
      Wind, temperature, pressure, humidity at maximum airplane
        height of 26,242 feet.
      Stratosphere:
        Lower level in winter than in summer.
        Lower temperature in summer when surface pressure is
          high.
    Definition:
      “Troposphere” is the physical laboratory where cloud
        and rain are produced by local causes and induced
        by the effect of the dynamical changes in the upper air.
      Conditions within 6 or 7 miles of the earth’s surface.
  Clouds and their Meaning:
    Cirrus:
      Height and composition.
      Formation:
        Perpendicular shafts of clouds indicate rapid changes
          in weather.
        Horizontal layers, no change and clouds will dissipate.
    Cirro-stratus, threatening in winter.
    Cirro-cumulus, fair and foul varieties differentiated.
    Cumulus with strong uplift.
    Alto-cumulus, cause of parallel rows.
    Fracto-cumulus, wind indicator, Point Loma “woolly.”
    Stratus.
    Alto-stratus, favorable for flying.
    Strato-cumulus, long shallow rolls, threatening in winter.
    Cumulo-nimbus, unsafe air conditions for flying.
    Fracto-nimbus, waterspouts and their causes.
    Velo cloud, examples, cause, effect, distribution, density.
    Fog, examples of great fog-belts.




CHAPTER III

NARRATIVE OF WEATHER OBSERVATIONS FROM AN AIRPLANE


In order to qualify as meteorologist competent to confer with aviators,
it seemed desirable to become personally acquainted with some of
the conditions that confronted them. As a matter of professional
acquirement therefore, I was glad to accept an invitation to go aloft
after the necessary official arrangements had been made with Washington.

This trip was in line with the previous endeavors of applying practical
meteorology to the science of flight and appropriately extended the
work which was begun in San Diego with Chanute and the sea-gulls
fifteen years before.

_Object of Flight._--I wished to put myself in the student’s place
and learn at first hand the practical facts he demanded from weather
observations and to acquaint myself with everything possible that might
be of value to an aviator. There were two definite things of which I
desired knowledge: first, to determine the height of the upward trend
of the sea-breeze over Point Loma which causes the mysterious “woolly”
of a score of years’ acquaintance from a yachting standpoint; second,
to observe the extent, form, and composition of the velo cloud which is
the characteristic sun-cover of California.

_Preparations for the Ascent._--Aviator Instructor Oscar Brindley
(the 1915 winner of the Curtiss trophy), in military tractor No.
50, was assigned as pilot. It may be stated here that the accepted
definition of aviator is a pilot of a flying-machine heavier than air.
The airplane used in my first flight (see Fig. 13) was made in Los
Angeles and is the present standard army model. This tractor has an
80-horsepower engine and 8-foot propeller. It is 21 feet long, has a
wing-spread of 38 feet, supporting area 364 square feet, and a flying
radius, with two persons, of 300 miles. The maximum altitude attained
with this model at San Diego was 13,000 feet. Before being placed in
service the machines are thoroughly gone over at the repair shop (see
Fig. 22), and the motors are run at full speed for twenty-four hours,
after which they are taken down and subjected to scrutiny for possible
defects. All of the struts, guys, and wires are closely examined; the
boltheads are all drilled, wired, and soldered so that no amount of
vibration will loosen them. Regardless of the length of the flight,
each machine, before going up again, is given a rigid inspection and
not until the mechanicians have tested every part is it pronounced
ready.

Not being prepared with a regulation aviation suit, I was loaned a
leather jacket by one officer, face-goggles and safety helmet by
others. I then took my place in the observer’s seat forward and was
strapped into it with the safety belt (see Fig. 12). I was cautioned to
let my body give way as the waist-controls were moved from side to side
and not pay any attention to the steering rudder wheel which had a way
of mysteriously revolving, advancing and receding.

In cranking an airplane, a certain formula is always gone through. The
mechanician at the propeller calls out, “Close!” The aviator closes
the switch and repeats the word. This short-circuits the ignition
apparatus so that no spark occurs in the cylinders. The propeller is
turned in order to introduce explosive mixtures into the cylinders.
When ready to start the mechanician says “Open!” The aviator opens the
switch and repeats the word. The charges in the cylinders then fire
when the propeller is turned.

After the engine starts, the machine is “trimmed” by helpers and
jockeyed for a favorable “take-off” into the air. (See Figs. 14, 15.)
This model of airplane climbs on a gradient 1 to 7; its minimum speed
is 41 miles per hour. In other words, if the speed is less than 41
miles per hour the machine will not fly horizontally.

_The Ascent._--The tractor was headed into a 30-mile northwesterly
wind so that the “take-off” was quick and easy; there were only a few
seconds spent rolling over the field, when the airplane left the ground
and I felt the never to be forgotten cushioning feeling of the air.
For ten seconds there was experienced a decidedly weakening nervous
chill, which occurred to me once before when making a high dive from
a spring-board. It was the sort of physiological disturbance that can
only be counteracted by immediately pulling one’s self together saying,
“_Well, here goes nothing!_” The momentary depression was immediately
followed by a corresponding elation of feeling which strange to say did
not leave me during the trip and is always associated with thoughts
of the journey. There was no dizziness, although I am peculiarly
susceptible to the least change in balance. The earth did not recede
as we progressed steadily upward; we seemed part of the earth, but
not of it. Although the airplane reached an altitude of 3,000 feet in
a comparatively few minutes, the barometer falling from 30.0 to 27.0
inches, the decreased bodily pressure was not at all noticeable.[H]

    [H] Trans-American Climatic Association, 1915, 31:20, Hot
        Springs, Va.

Next to the supporting quality of the atmosphere I had noticed the
70-mile blast of air as the airplane pushed its way steadily onward and
upward. Naturally, the exhaust of the motor in addition to the roar of
the wind made conversation impossible. Some airplanes have telephone
communication between observer and pilot. (See Fig. 9.) During one
flight in a machine not so equipped, the passenger noticed the breaking
of some apparatus. Knowing that it was impossible to make himself heard
he hastily scribbled the word “Accident!” on a bit of card, whereupon
the pilot shut off his engine and glided to earth.

_Two-thousand Feet above Point Loma._--Carrying out my suggestion as
to investigating the “woolly,” the pilot drove the machine straight
for Point Loma and those unseen aërial breakers. Suddenly there were
two distinct “wallops” and I felt the fuselage beneath me respond as
if struck by a stuffed club. There was evidently first a surge then
a drop, and it was the descending current of air that deprived the
airplane of the supporting medium, hence the shock. Point Loma itself,
from this altitude, and seen directly from above, looked very like a
barracuda’s backbone--long, low, and ugly. Although this peninsula (see
Fig. 21) is less than 500 feet high it so effectively deflects the
prevailing northwesterly wind that the upward surge has been noticed by
aviators at an altitude of 4,000 feet. It is no wonder then that these
descending winds, called “woollies” (from their churning the water into
isolated masses which look like tufts of wool), are dreaded alike by
yachtsmen and birdmen. They have been known to carry away topsails from
too closely venturing schooners and student aviators always give the
vicinity of Point Loma a wide berth.

_No Winds Aloft._--We had not changed our direction since leaving the
ground, but after passing over Point Loma the airplane was put sharply
on a port course. I had been expecting this and must confess, somewhat
dreaded it, innocently thinking that a 30-mile wind added to our
70-mile rate of speed would “heel” the craft to an uncomfortable angle
when the course was changed from northwesterly to southerly. What was
my astonishment to find that the putting about was unaccompanied by
any of the nautical motions such as tilting or canting. Theoretically
one may be ever so well grounded in physical laws but it seems to take
actual experience to bring their truth home to us. Of course there can
be no wind in the air; when we entered the air it was moving 30 miles
an hour in relation to the earth but as soon as we were free from the
earth the velocity of the wind had no effect on our flight. No matter
how strong the gale, so far as it concerned the airplane, if the wind
be steady no difficulty is experienced; the aviator is concerned only
by wind-shifts.

_The Velo Cloud Seen from Above._--In kindergarten days I remember that
one of the first questions I asked was “Are clouds smoke?” And this
early query was really first answered in the air. Fog on a mountain
top may be cloud, but somehow cloud free from close proximity to the
earth seems different.

The machine was put through the cloud blanket much as a horse takes
a hurdle; it seemed unlike fog and more of a palpable substance. As
we emerged, the sun was shining on it like a silvery sea with gently
undulating surfaces and it looked for all the world as supportable
as layers of cotton-wool. Many times have cloud-banks from mountain
tops been observed, yet the upper side of the velo cloud from a
flying-machine looked very different. The cloud was only four or
five hundred feet thick and extended inland a few miles in irregular
outline. The seaward edges of the velo cloud were not ragged, and
apparently paralleled the coast for 10 or 15 miles.

Such was the exhilaration and confidence the air gave that I can
understand how parachute jumpers confidently step off into space,
for to them the air is a supporting medium no more terrible than a
transparent sea to a good swimmer. I believe that the record parachute
drop was made in 1916 by Colonel Maitland, of the English Royal Flying
Corps, who descended in a parachute 10,000 feet from an airplane.
Fifteen minutes was occupied in the descent.

_Ease of Vision at 3,500 Feet Altitude._--At this altitude the ease of
vision is most remarkable. At this height, _with perpendicular vision_,
the eye is possessed of wonderful powers. In those “solitudes august
with stars” men not only “mount up with wings as eagles” but are given
the eagle’s unobstructed vision. Birds have been credited with much too
keen vision. From this height of several thousand feet every object
stood out with remarkable distinctness. Automobiles racing along the
El Cajon boulevard to Lakeside were readily picked up with the unaided
eye although 20 miles away. Looking down over the aviation field the
long compass mark and the wind-direction pennant (Figs. 19 and 20)
were easily distinguished. The bay and ocean, however, gave the most
remarkable revelation, for the bottom of the bay and the shallow ocean
shore were plainly discernible. The absence of water as well as air
refraction explains why submarines cannot hide from an airplane: one of
the army aviators told me that a submarine cannot ordinarily sink so
low that it cannot be seen from an airplane.

_Color of Landing-ground Important._--Owing to the absorption and
reflection of sunlight, there is a distinct variation in the character
of otherwise similar landing-ground. A field, dark from recent plowing
(or burning), will heat the air over it faster than will a field of
stubble, hence over the former field there will be the greater air
disturbance, and this will affect the ease of landing. Air is heated
by contact and convection. One of the aviators said that recently he
was descending, and had all but reached the ground when a localized
convectional current hurled his machine upward some distance but
immediately afterward deposited him on the ground without damage.

_Spiraling Down 3,000 Feet._--Speeding ever in wide circles the course
lay southeast over the upper part of San Diego Bay. The city of San
Diego presented the usual checkerboard appearance (Fig. 16), and
even at this altitude it would seem easy to drop an orange at almost
any point. The velo cloud was lifting and we could see the gradual
disappearance as it melted rather than drifted from North Island. (See
Fig. 17.)

The gliding descent was made from an altitude of 2,500 feet, starting
above San Diego. As the aviation school was approached, we could see a
number of machines in the air, three below and two above us, circling
about like hawks. And, like soaring birds, these machines had their
air-lanes, designated courses and levels being devoted to the different
classes of machines. The landing was made without incident and the
hour’s flight was ended.

_Outline of Meteorological Work at the Aviation School._--At the close
of the lecture detail, the attention of the student aviators was called
to the importance of their having as thorough knowledge as possible of
the fundamentals of meteorology. The application of these fundamentals
to the analysis of air conditions met with in their daily flights was
shown to be essential. Investigations as to varying wind direction were
taken up by one of the staff instructors by the use of small parachutes
to be dropped at different altitudes. (See Fig. 8.) Through the
coöperation of the local official in charge of the San Diego Weather
Bureau station, duplicate signal sheets were available from which the
student officers made their local weather maps. From these maps and
their own flights, they could arrive at some relationship between the
actual and the theoretical 3,000- and 10,000-foot level maps prepared
from the Bigelow formula, as used by the Bureau. Lectures were given
on temperature and its distribution; winds, moisture, and clouds were
also made part of the course, one of the papers of the Bureau[I] being
reprinted by the aviation school by permission of the Chief of the
Bureau and used as a textbook. The Weather Bureau furnished the station
with a standard set of meteorological instruments so that the student
officers could become perfectly familiar with the regular equipment at
the Weather Bureau stations.

    [I] “Clouds of California,” Carpenter, 1914, 24, 2d ed., Ft.
        Leavenworth (U. S. Army Press).

_Extending the Usefulness of the Bureau to the Aviators._--Practical
utilization by the aviators of this district of the information
possessed by the Bureau has received considerable impetus during the
past six months. During the cross-country flights of April and May,
1916, the Los Angeles station was directed by the Chief of Bureau
to furnish weather and flight conditions between San Diego and Los
Angeles. With the aid of the general weather-map data from the regular
stations, and special observations of wind, weather, and fog conditions
on the immediate coast near Los Angeles, and on Mount Wilson, it
was possible to issue satisfactory forecasts of flying conditions.
The eye-observations of fog-heights as determined by the Weather
Bureau coöperative station at the Mount Wilson Solar Observatory were
especially valuable. From this mountain (6,000 feet elevation) it
is possible on a good day to see the whole length of the coast from
Point Firmin, San Pedro harbor to Point Loma, San Diego Bay. Knowing
different levels, the observer at Mount Wilson was able to give actual
thickness and extent of the fog-belt and its past twenty-four-hour
history.




CHAPTER IV

INVESTIGATING THE UPPER AIR


_Balloon Soundings into the Stratosphere._--It was the writer’s
privilege to be present when some highly interesting and instructive
experiments made by the Weather Bureau in coöperation with the
Smithsonian Institution, in sounding the upper air were made at Avalon,
Santa Catalina Island, off the coast of southern California in July
and August, 1913.[J] The results of this work were in close agreement
with similar soundings of the upper air throughout other surveyed
portions of the earth’s atmosphere, and a record ascension for this
country was made on July 30--32,643 meters or 20½ miles. In common with
other observations of temperatures in the stratosphere, the minimum
temperature of these soundings (-90 F., August 3) was registered within
the first 10 miles.[K]

    [J] University of California Chronicle, 1915, 17:1–25, Berkeley.

    [K] Monthly Weather Review, 1914, 42:410, Washington.

Of especial interest to the aviator is the table on the next page
which shows wind velocities increasing with elevation as determined by
observations of the Avalon balloons.


RECORD OF AVALON ASCENTS, JULY-AUGUST, 1913

_Table showing Theodolite observations of wind velocities (meters per
second) at elevations of 1,000 and 5,000 meters_

  ======+=======+=======+=======+=======+=======+======+======+======+====
        |Meters |Meters |Meters |Meters |Meters |Meters|Meters|Meters|
        | per   | per   | per   | per   | per   | per  | per  | per  |
  Meters|second |second |second |second |second |second|second|second|Mean
        |5 p.m. |5 p.m. |10 a.m.|10 a.m.|10 a.m.|5 p.m.|4 p.m.|5 p.m.|
        |July 24|July 27|July 31|Aug. 1 |Aug. 2 |Aug. 3|Aug. 7|Aug. 8|
  ------+-------+-------+-------+-------+-------+------+------+------+----
  1,000 |  2.5  |  1.0  |  5.6  |  6.6  |  2.3  |  5.8 |  7.1 |  1.9 | 4.1
  1,500 |  6.2  |  0.8  |  6.2  |  8.1  |  3.3  |  5.0 |  6.4 |  1.5 | 4.7
  2,000 |  8.0  |  1.2  |  5.8  |  7.0  |  4.1  |  4.5 |  6.5 |  6.0 | 5.4
  2,500 | 10.0  |  1.8  | 10.8  |  5.7  |  5.2  |  4.2 |  4.7 |  3.6 | 5.8
  3,000 | 12.0  |  2.3  |  9.4  |  6.1  |  7.2  |  5.2 |  3.5 |  4.1 | 6.2
  3,500 | 12.8  |  2.5  |  8.0  |  6.7  |  7.4  |  6.1 |  4.6 |  4.6 | 6.6
  4,000 | 13.6  |  3.8  | 11.2  |  7.4  |  9.2  |  5.2 |  6.4 |  3.2 | 7.5
  4,500 | 14.3  |  5.2  | 14.6  |  8.5  | 11.2  |  1.8 |  7.8 |  3.0 | 8.3
  5,000 | 21.2  |  6.2  | 12.8  | 10.3  | 10.4  |  2.3 |      |  3.4 | 9.5
  ------+-------+-------+-------+-------+-------+------+------+------+----


_Charts Showing Upper-air Weather Conditions._--It is believed that
the following charts when examined in connection with the accompanying
explanation in the text will give the reader something of an outline as
to the conditions existing in the upper regions of the atmosphere.


[Illustration: CHART NO. 1

_Horizontal Projections of the Paths of the Sounding Balloons Liberated
at Avalon, California, July 23 to August 10, 1913_

    Reproduced from the _Monthly Weather Review_, 42: 423

    This figure shows the horizontal projections as far as the
    balloon was observed, not the entire distance traveled until it
    landed.]


[Illustration: CHART NO. 2

_Vertical Temperature Gradient, Avalon, California, July 27, 1913_

    Solid line represents the ascent of the recording apparatus,
    the dotted line the descent. (Verticals 25° C. or 45° F.)

Reproduced from the _Monthly Weather Review_, 42: 412]


[Illustration: CHART NO. 3

_Mean Vertical Temperature Gradient_

    Figure reproduced from _Monthly Weather Review_, 42: 413.

    Altitude values are in kilometers at the left, and in miles at
    the right: Temperature values are in Centigrade at bottom, in
    Fahrenheit at top.

    Maximum airplane altitude 26,242 feet or 5 miles.]


[Illustration: CHART NO. 4

_Diagram Showing Increase of Wind with Elevation Data from Eight
Meteorographs_

    From the article “Free Air Data in Southern California,
    July and August, 1913” by Dr. Wm. R. Blair, Professor of
    Meteorology, in the _Monthly Weather Review_, for July, 1914,
    it is learned that the wind shifts from west to east rather
    abruptly at 16 to 20 km. (10 to 12 miles); below this level
    down to about 5 km. (3 miles) it is quite uniformly from the
    west. Extremes: Maximum wind velocity 21.2 miles, 5,000 meters
    elevation, 5 P.M., July 24; minimum wind velocity 0.8 miles,
    1,500 meters elevation, 5 P.M., July 27.

    The table shows a steady increase in velocity of the wind
    with elevation, the data being obtained from the eight
    meteorographs. There were four morning flights (July 31, August
    3, 7, 8) and five afternoon flights (July 24, 27, August 3, 7,
    8, 1913), and elevations were computed for nine heights, 1,000
    to 5,000 meters. Beyond the 5,000 meters the records show that
    from 2 to 7 miles altitude the wind increases at approximately
    the same rate that the density of the air decreases.]


[Illustration: CHART NO. 5

_Chart Showing Number of Flights and Duration in Hours for the Months
of July to December, 1915, and January to August, 1916_

    Prepared by the War Department, Signal Corps Aviation School,
    San Diego, California, and furnished through the courtesy of
    Col. W. A. Glassford, Signal Corps, U. S. Army, Commanding
    Officer, September 14, 1916.]


[Illustration: FIG. 1. CONGRESSIONAL MEDAL AWARDED WRIGHT BROTHERS

(_Designed by Morgan_)

    This medal was awarded Orville and Wilbur Wright by resolution
    of Congress, March 4, 1909. Bronze replica in possession of the
    writer.

_Photographed May 31, 1916, by permission of the Director of the Mint,
Philadelphia_]


[Illustration: FIG. 2. ASCENT OF SOUNDING-BALLOONS AT AVALON

_Photographed July 27, 1913_

    This set was liberated from the base of the U. S. Weather
    Bureau, Avalon, Catalina Island, California, at 4.57 P.M., July
    27, 1913, and rose to a height of 23,870 meters in one hour and
    three quarters when one of the balloons burst and the descent
    began. This was observed by Carpenter at the theodolite.]


[Illustration: FIG. 3. METROGRAPH WHICH MADE THE ASCENT OF JULY 27, 1913

_Photographed August, 1913_

    This meteorograph rose to a height of 23,870 meters (94,716
    feet), at which height the pressure was 23 mm. (0.906 inches),
    temperature -52.1 C (-58 F.), relative humidity 21 per cent,
    wind E. (or more precisely S. 79 degrees E.), velocity 6.1
    m.p.s. (14 miles per hour), but the minimum temperature was
    registered at 15,228 meters (49,960 feet) when the thermometer
    showed -64.7 C. (-85 F.), at which time the pressure was 89 mm.
    (3.504 inches of the barometer), relative humidity 19 per cent,
    wind N.W., 3.4 m.p.s. (8 miles per hour).

    The basket was picked up at sea off Oceanside, San Diego
    County, about 90 km. (145 miles) east of Avalon.

    For the first 6 miles of ascension the balloon moved upward at
    the rate of 8 miles per hour.]


[Illustration: FIG. 4. FIRST FLIGHT OF AIRPLANE CARRYING TWO PERSONS

_Photographed September 10, 1908_

    This photograph was made at Fort Meyer, Virginia, of the
    original Wright biplane, piloted by Mr. Orville Wright With
    Colonel G. O. Squier, U. S. A., as first passenger.

    When this photograph was made no fatalities in airplane
    flight had occurred; the first victim, Lieutenant Selfridge,
    U. S. A., was killed while riding with Mr. Wright in the same
    biplane shown above, on the Tuesday following the Saturday this
    photograph was made, the machine falling to the ground at a
    spot which is practically the center of the picture, but near
    the trees which are part of Arlington National Cemetery.]


[Illustration: FIG. 5. MOUNT WILSON OBSERVATORY

_Photographed December 24, 1915_

    A special meteorological station of the Weather Bureau was
    established on Mount Wilson, December 25, 1915, and on April
    1, 1916, daily reports of temperature, weather, precipitation,
    relative humidity, fog and other conditions were first
    telegraphed to the local office of the Weather Bureau at Los
    Angeles for publication and distribution.

    The photograph shows the location of the meteorological
    observatory(*) and the valleys below. From the elevation of
    the observatory (6,000 feet above sea-level), it is possible
    for the observer to determine the thickness and extent of fog
    as it is feasible to see as far southwesterly as Point Loma
    on a clear day, and southerly to Santa Catalina Island. Such
    observations and reports have been made and forwarded without
    interruption to date. They have proven of incalculable value to
    the aviators making cross-country flights.

    The station on Mount Wilson is maintained through the
    coöperation of the Carnegie Institute of Washington.]


[Illustration: FIG. 6. TYPE OF AIRPLANE USED IN 1911 ON NORTH ISLAND

_Photographed October, 1911_

    This photograph of Mr. Glenn Curtiss in his “pusher” airplane
    was made shortly after the Curtiss School of Flying was
    established in 1911, on North Island. At his right is Local
    Forecaster Carpenter.

    Comparison of this machine, which four years ago was the last
    word in airplanes, with the tractor shown on the opposite page,
    indicates the rapid progress in design.]


[Illustration: FIG. 7. DISCUSSING A FLIGHT

_Photographed October 18, 1915_

    Aviation Instructor Oscar Brindley discussing a flight with
    Captain Clarke, U. S. A., and other officers at the U. S.
    Aviation School at San Diego.

    Mr. Brindley is standing by the side of Captain Clarke in the
    group at the right. After every flight the Instructor reviews,
    point by point, the features of the flight, showing the pupil
    his deficiencies and explaining how he may avoid them in the
    future.

    The officer at the left, Lieutenant Brown, has the regulation
    leather leggings, coat and helmet, and is ready to go up as
    soon as the mechanicians (who may be seen at the extreme left)
    finish inspection and pronounce the airplane fit for the next
    flight.]


[Illustration: FIG. 8. CAPTAIN CULVER AND PARACHUTE

_Photographed October 21, 1915_

    Captain C. C. Culver, U. S. Cavalry, Adjutant, Aviation School,
    with a parachute in his hand, having word with Captain L. W.
    Patterson, U. S. A., before the latter’s flight. The object
    of the parachute is to determine changing wind-direction at
    different heights.

    The airplane wireless record is now held by Captain Culver. In
    October, 1916, he sent a message 119 miles from Santa Monica
    to San Diego, California, while flying at an altitude of 1½
    miles. He received a radio message from a distance of 11 miles
    while flying 7,000 feet aloft. He is also the first military
    aviator to rig up two airplanes so that they could exchange
    messages while in flight. The radio set used weighed less than
    forty-five pounds.]


[Illustration: FIG. 9. LIEUTENANT GORRELL, U. S. INFANTRY, AS OBSERVER

_Photographed October, 1915_

    The noise of the motor, together with the terrific blast of
    air, makes conversation impossible between the pilot and
    observer; for that reason telephones are sometimes installed as
    noted in this photograph.

    Lieut. Edgar S. Gorrell is shown as the observer in this
    photograph. He has since qualified as an aviator and made a
    brilliant record in the Mexican activities in 1916.]


[Illustration: FIG. 10. POINT LOMA FROM THE EASTERN SHORE OF NORTH
ISLAND

_Photographed October, 1915_

    The peninsula of Point Loma rises to an elevation approximating
    500 feet, and as it lies approximately north and south, it
    interposes a considerable barrier to the prevailing westerly
    winds. The eastern side of Point Loma is very precipitous.
    These factors tend to produce winds called “woollies” which are
    a distinct menace to all small boats and air-craft, unless the
    air-craft have an elevation exceeding 3,000 feet on a normal
    windy day.]


[Illustration: FIG. 11. SAN DIEGO, ACROSS SPANISH BIGHT, AS SEEN FROM
THE U. S. AVIATION SCHOOL AT TWILIGHT

_Photographed October, 1915_

    Contrasted with the photograph of Point Loma on the opposite
    page, this picture shows the ideal water conditions for trying
    out seaplanes. Shortly before this picture was taken, one of
    the pilots of the Curtiss Aviation School, also on North Island
    drove a big seaplane 100 miles per hour barely skimming the
    surface of the water.]


[Illustration: FIG. 12. INSTRUCTOR BRINDLEY AND METEOROLOGIST CARPENTER
IN MILITARY TRACTOR NO. 50

_Photographed October 20, 1915_

    Instructor Oscar Brindley and the observer, Meteorologist Ford
    A. Carpenter, U. S. Weather Bureau, leaving the ground for a
    flight. In the military tractor used generally by the Army,
    the observer sits forward while the pilot occupies the after
    cockpit. This machine, like all others used in the military
    service, has dual control.]


[Illustration: FIG. 13. MILITARY TRACTOR NO. 50. TYPE OF BIPLANE USED
IN U. S. ARMY SERVICE MADE BY GLENN MARTIN, LOS ANGELES, CAL.

_Photographed October, 1915_

  Motor, horsepower, 80: revolutions per minute, 1,277.
  Diameter of propeller, 8 feet.
  Load of 39 gallons gasoline, 2½ gallons oil.
  Flying radius with normal equipment, two persons, 300 miles.
  Maximum altitude obtained with this model at San Diego, 13,000 feet.
  Wing-spread, tip to tip, upper, 38 feet, 10 inches; lower, 34 feet,
      10 inches.
  Supporting area, upper, 139 square feet; lower, 165 square feet;
      total, 364 square feet.
  Length of fuselage from rear of propeller hub, 21 feet, 6¾ inches.
  Data from Major F. P. Lahm, Signal Corps, U. S. A.
  Dated May 9, 1916.]


[Illustration: FIG. 14. “TRIMMING” A TRACTOR IN LEAVING THE GROUND

_Photographed October, 1915_

    Military Tractor No. 50 just before leaving the ground. In
    gusty weather the mechanicians steady the ends of the lower
    planes, sometimes turning it by holding one edge and pushing
    the other. In the photograph the mechanicians are giving the
    airplane steerageway to the right.]


[Illustration: FIG. 15. MILITARY TRACTOR NO. 50 JUST LEAVING THE GROUND

_Photographed October, 1915_

    Before attempting to leave the ground there is always
    considerable jockeying for a favorable head-wind, and the
    photograph shows Instructor Brindley maneuvering for a
    favorable pointing.

    After leaving the ground, the wind, so long as it is not gusty,
    makes no difference to the pilot.]


[Illustration: FIG. 16. SAN DIEGO HARBOR AT OVER 2,000 FEET ALTITUDE

_Photographed October, 1915_

    The new municipal wharves are in the middle foreground and to
    their right may be seen the Santa Fé station. Part of North
    Island is obscured by cloud.]


[Illustration: FIG. 17. THIRTY-FIVE HUNDRED FEET ABOVE SAN DIEGO

_Photographed October, 1915_

    This photograph was made 1,000 feet above the clouds. The
    wharves of San Diego and Coronado may be seen in the foreground
    and in the middle distance.]


[Illustration: FIG. 18. MILITARY TRACTOR NO. 50 AT 3,500 FEET ALTITUDE

_Photographed October 20, 1915_

    The airplane, in which the pilot, Oscar Brindley and the
    observer, Meteorologist Carpenter, made their flight, was
    photographed at the maximum elevation, 3,500 feet above the
    aviation field.]


[Illustration: FIG. 19. FLYING SQUAD’S WIND-DIRECTION PENNANT ON TOWER

_Photographed October 5, 1915_

    The regular observation tower from which all observations and
    notes on every flight are made is just back of the headquarters
    building. The station anemometer is on the tower, and the
    portable anemometer is to the left.]


[Illustration: FIG. 20. THE AVIATION SCHOOL MOTOR-BOAT “PRONTO”

_Photographed October, 1915_

    During the flying periods, the motor-boat of the U. S. Aviation
    School is kept ready for instant service in order to work in
    conjunction, if needs be, with the Medical Corps emergency
    truck on land.

    Such is the speed of this boat (exceeding 40 miles per hour)
    that the water no longer has resiliency, and it is about as
    comfortable as riding in an old-fashioned stone-boat over rocky
    pastures.]


[Illustration: FIG. 21. U. S. AVIATION FIELD AT THREE THOUSAND FEET
ALTITUDE

_Photographed October, 1915_

    Part of Coronado and the portion of land called North Island,
    separated by Spanish Bight. Point Loma may be seen at the
    extreme upper right-hand corner of the photograph. The
    flying-machine sheds, buildings of the Aviation School, etc.,
    may be seen in the immediate foreground. The U. S. Cavalry camp
    is the white splotch in the center foreground.]


[Illustration: FIG. 22. REPAIR SHOP U. S. AVIATION SCHOOL, SAN DIEGO,
CAL.

_Photographed October, 1915_

    In the repair shop of the U. S. Aviation School at North Island
    the motors are given a gruelling test, being run twenty-four
    consecutive hours at a speed greater than that given them in
    actual practice. After this run they are taken down and each
    part is spread out on a large drawing-table and is subjected to
    close scrutiny so as to show any defect. Several airplanes as
    well as seaplanes have been reconstructed in this shop.]




      *      *      *      *      *      *




Transcriber’s note:

Punctuation and spelling were made consistent when a predominant
preference was found in this book; otherwise they were not changed.

Simple typographical errors were corrected.

Ambiguous hyphens at the ends of lines were retained; occurrences of
inconsistent hyphenation have not been changed.