Flying as Fast as the Speed of Sound
SINCE the flying rate of airplane?,
during the last 19 years, has been
increased front 50 miles to more
than 100 miles an hour and the fact that
man feels no discomfort, apart from the
noise of the engine, when traveling
steadily at the record-breaking speed, is
encouraging aviation experts to look
ahead to still greater speeds until it
may be possible to reach a point some
where near the speed at which sound
travels, which is 740 miles an hour or
feet a second.
"The question might reasonably be
asked whether the speed of sound might
be reached for a short time, say one
minute. a« many mall and a few large
projectiles start their flight, at speeds
greater than that of sound.” says J, h.
Naylor, M. A., in the Scientific Ameri
can,
“’To attain or exceed the speed of sound
by any known method except a rocket
Will need a high acceleration for many
seconds, so that experiments in this di
rection are not likely to produce good
results. Moreover1, even with rockets
When Mosquitoes
Bite Their Worst
PERIODS when mosquitoes bite
best,-or worst, have been revealed
by entomologists of the Unifed
States Department of Agriculture.
Some mosquitoes bite only at night,
while others bite only during the day.
Some* bite most at sunrise, and others
are busiest at sundown. .
Only the female mosquito bites. The
male feeds on nectar and similar sub
stances from plants.
The ‘‘rain barrel” or common mos
quito bites only at night. When flying
it makes a singing noise.
The vellow-fever mosquito usually
bites only in the daytime and is busiest
early in the morning and late in the
afternoon. It flics quietly. It will bite
indoors all day.
The fresh-water marsh mosquito is
busiest just at dusk. It spends the day
in the grass and will bite during the
day if disturbed.
Malarial mosquitoes will bit* all
nright long and on dark days.
the difficulty of landinic safely will bo
great even with an airplane structure;
in fact, Herr Opel’s experiments on roc
ket cars and airplanes have not been so
successful as to warrant a vigorous
piosecution of this line of research.
“In another way high accelerations
are sure to be incurred as it is necessary
to return at some time to a starting:
point.
' I he amount of
arcrleratior? e x -
perieneed i n a
fast modern air
plane during a
tight turn is a
measure of the
p i 1 o t’s feeling'
rather than the
speed of the air
craft, as he is
trained not to ex
cifd certain
stresses so as not
to break the struc
ture. Considering
the simple turn it
is immediately ob
vious that turn
ing on the same
circle at 400 miles
per hour will put
on stresses nine
times as high as
183.3 miles per
hour, a fast cruis
ing speed for a
civil airplane
The alternative is
to turn in a wider
circle, ivhich in
view of the speed
reached meana a
verj wide sweep.
Therefore, very
high speed air
craft are going to
need large maneuver areas, apart from
any considerations of the distances re
quired to take off and land even under
ideal conditions.
“In the high-speed car problem, the
The Strange7Tree of Destiny77
That Sheds*Its Blood
GROWING at the foot of the Acro
polis, one of the most, famous
ruins of antiquity, is one of the
strangest, phenomena of all plant life—
a tree which is described as literally
bleeding itself to death.
Early each June this mysterious
woody plant, which is known as the
“Tree of Destiny,” shoots its long trunks
into the air as if by magic out of a soil
apparently devoid of all nourishment.
After several weeks when the trunk
of this tree, which is also called the
"temple of the light of the Acropolis,”
because of its resemblance on occasions
to a giant candelabra, it suddenly ex
tends its branches at the ends of which
appear spongelike growths. At ma
turity the tree bursts into a mass of
crimson blossoms from which drop a
liquid that has the appearance of blood.
When the last blossom has shed its last
drop of “blood” the tree then dies and
its trunks become fragil, hollow, stalks
that are easily broken by the first wind
that blows.
The “Tree of Destiny,” which reaches
maturity within two months after its
shoot has thrust its head above ground,
is supposed to obtain its nourishment
from large parasitic plants growing at
its base. These plants closely resemble
the cactus that grows on American
1 deserts, although the leaves are not as
coarse, but they have sawlike edges and
are sharply pointed.
L
Abo*e: l.hnitrntag a High
S|ifrd Airplane in a Re
rrnll* Inaugurated One
liar Tranarontinenlal
Passenger Service. An
Early StageCoach b Shown
at the Right. Rig
Head-on View of a
Apeert-Plahe Show ing
ihe Small Fron
tal Area.
runs have been along straight atretches.
the car losing most, of its speed before
turning for a run in the opposite direc
tion ; as in only a few parts of the world
are there long straight flat stretches of
ground, very high speed motors must
remain a pure sport without any com
mercial development other than a strm
gent test of materials, manufacture and
design. The aircraft, once it is in the
air, does not suffer from this restric
tion. hut it is dependent on the care
needed not to overstrain the human
body. The high-speed aircraft for the
average flier will, therefore, hava to be
flown with eare and have large areas in
whicji to maneuver. Apart from this
need for care, there is at present no
limitation imposed on 'high speeds by
the mere human factor.
“Until races are inaugurated on pilot
less aircraft controlled by wireless or
some other means, the first essential is to
Glass Blackboards
THE familiar slate blackboard of
the schoolroom may soon be rele
gated to the past and its place
taken by blackboards of glass. _
Slate, and particularly slate suitable
for blackboards, is a natural product
found in a restricted area in eastern
Pennsylvania, according to The Chemi
cal Digest. It is inevitable that it even
tually will be exhausted. Hence the sub
stitution of glass.
The problem was one of developing
glass by treating it in such a way that
it could be given a surface as fine and
velvety as slate, and at the same time
he perfectly durable by incorporating a
fine abrasive.
The tests show perfect results. The
glass board is approximately the same
thickness, weighs the same per square
foot and is erected in exactly the same
way as slate.
When This Mr*terr Tree Mature*.' It
Bursts Into a Mass of Crimson Blossom*
from TCHirh Flo“ a Woodlike Liquid.
The Tree Then Dies end Its Trunk Be.
come* a Fragile. Hollow Stalk.
a
How Mortar Is Strensthened with Susar
MORTAR made* of lime-sand,
when sweetened with cane
sugar, Is greatly strengthened,
according to a paper presented before
the Sugar Division of the American
Chemical Society recently by Drs. Ger
ald J. Cox and John Metschl, of the
Mellon Institute of Industrial Research,
at Pittsburgh. Such an application of
sugar is not new, as it is believed that
the Romans made use of such materials
in mortars that have certainly stood the
test of time. Also, in sugar-growing
countries, it is known that sugar hss
b«»n employed to increase the strength
of mortar.
Drt 'Cox and Metschl found thet there
is rerv good reason for the empirical
practice of “sweetening” mortar. From
their experiments they ascertained that
mortar which contains sugar equal to 6
percent of the quick-lime content has a
tensile strength 60 percent greater than
that of mortar containing no sugar.
Further tests are planned of compres
sion strength, setting time, and dura
bility as influenced by cane sugar.
The process of mixing the sugar with
the mortar is quite simple. The sugar is
dissolved in part of the gaging water and
mixed in with the sand and lime. The
sugar must not be mixed with the lime
before slaking.
‘ With the present low price of sugar.
tHeflve or six pounds of sugar necessary
fOr 100 pounds of lime fs only a sm.sli
addition to the cost of laying bricks or
plastering a wall.
FMtUTM 8f
Hou) Experts in Aviation Plan a
New Engine That Can Drive An
Airplane at the Rate oj 1,080
Feet a Second.
I.efli A Pilot Shown in
Contra*! with thr l.n
■ine (Shaded Part) to
Indicate the Degree
of Streamlining. Right.
Thia ('.hart Show* llnw
Airplane Speed* in 19
Year* Have lnerra*eil
from SO Mile* to 0*ei
400 Mile* an Hour.
carry a pilot. Anyone who has wen the
•mall space allowed for the driver of
the racing car and the smaller space for
the racing plane pilot will realize that
eery close attention has been paid to
presenting the minimum resistance to
. the air. If we take the frontal area of
a man sitting down a* four square feet,
then his resistance at 400 miles per hour
is of the order of 2,000 pounds, nearly
one ton.
“The frontal area of one of the most
efficient types of airplane yet developed
does not greatly exceed that of a sitting
map, being 40 inches high and 30 inches
wide, dimensions which permit of a
streamline body to enclose the pilot suit
ably behind it and a view forward be
tween the two banks of cylinder!. It
gains its 2300 brake horsepower at a
weight of 1630 pounds, representing a
ne wer increase over the 1020 engine of
21 per cent for a weight increase of six
and one-half per cent. From a calcula
tion based on the improvement attained
iri the speed record it would seem that
in the ‘sprint’ engine at. least another
300 horsepower must have been de
veloped for approximately the same total
, weight by running the engine at a higher
speed—a remarkable achievement.
“The high power developed by the en
gine means a great expenditure of heat.”
Mr. fv’aylor continues, “and this has to
be dissipated rapidly or else the engine
would overheat, and fail to function. A
rough idea of the rate of fuereonsumed
van He gaged
when it is
realized that
the gasoline is burned
faster than it ran be
pouted out of a two-gallon ran.
“At present there seems to
be no limit, in sight to the maxi
mum speed that ran he reached.
The curve given in the accompany
ing chart shows how the speeds
have increased steadily each year
and the anparejit slackening tiff in
1931 is due to the more severe
conditions of last year.
The speed record has.
however, j uinped forward
■ ri the two years by at
least the same amount as
previously.
(feurtm «f Th« !ki*nnfl# Aon«H(wn
“"hat then are the limitation*?
"IC the engine designer ran continue
to construct engines which will run still
faster without* proportional increaia in
weight, so that the weight per horse
power is still further reduced, then the'
aerodynamist will devise means, perhaps
using wings whose area can be altered
at will, so that the engine can he taken
into the air, be pulled at still higher
spends by the airscrew (which has by
no means reached its limits of design),
cooled by devices for making more effi
cient the available surfaces of the craft,,
and no doubt, if the power available be.
large enough, design a much larger body
into which the floats with their load of
fuel can be absorbed after the craft has
lift the water.
“Already there arc airplanes flying in
v hich arrangements have been made to
retract the undercarriage wheel* into
the body and floats may well be expected
to follow. The saving in resistance, if
floats and struts were omitted, would
amount to as much as one-half the total
for the whole aircraft. Given the neces
sary incentive and the funds, there ap
pears to bn no reason why speeds should
not continuously increase until they ap
proach the velocity of sound at 740 milas
per hour,” •
- -
4
Paint as a Thermometer
PAINT which will change color with
changes in temperature thereby in
dieating vleuafly the temperature
cycle through which the painted surface
passes under a given set of condition* is
the uniaue development described in
Chemical and Metallurgical Engineer
ing. This paint is made by mixing inti
mately one part by weight of cuprous
iodide with two parts of mercuric iodide,
either dry or with the addition of a lit
tle water. If water is employed, it must
be evaporated by the application of a
gentle heat at a temperature below 140
degrees Fahrenheit. When dry, the mix
ture should Ik- ground to a fine powder,
which is then mixed with a thin, light
colored, non-acid oil or spirit varnish.
The resulting paint i* applied with
brush..
Metals such as tinned iron or brass
may be given one or more coats, but the
paint should not he applied to aluminum
as the resulting chemical action destroys
the jjaint. A surface covered or striped
with this paint—(or example, a bearing 4
or machine pari—will be bright reo
from room temperature to 130 degrees
Fahrenheit, at which temperature per.
ceptible darkening occurs. At 135 de
green, the paint is noticeably darker and
at 145 degrees it is maroon. At 156 de
grees, it assumes a light chocolate
color; and at 160 degrees, it is dark
chocolate. When it has reached 190 de
grees, it attains the darkest, color that
can be distinguished; and at 212 degrees,
it is almost black.
In cooling, the color cycle Is reversed,
with the exception that the dark choco- >■'
late color appears at 170 decrees in
stead of 160 degrees, and temperatures
between 212 and 170 degrees are not
readily determinable, Below 170, the
colors re-appear at the temperatures in
dicated for the ascending scale, and the
cycle can he repeated as often as de
sired. A stripe of the paint on a hot
water tank will show readily the hot
water level.
Bringing the Jungle to the City
SHOULD you ever feel
the call of a thrilling:
adventure in the jun
gle it is now no longer neces
sary to organize an elabo
rate expedition and proceed
to some distant tropical land
in the heart of Africa or
India. All you have to do
today is to wend your way
Perfect Skins of Tigers
and Other Wild llrasls,
After Being Chemically
Treated. Are Stretched
Over Skilfully Sculp
tured Models oftfthc
Originals, Then Placed
in Natural Pose* and
Surrounded hy jungle
Scenery.
lo me American use urn ui
Natural History in New York City
where you can place yourself in the
midst of jungle surroundings of a
startling naturalness. The lure of the
dense and mysterious jungle with all of
its thrills has been brought to blase
Broadway and the habitues of that
glittering world-famed thoroughfare
now need to walk no farther than a few
city blocks before they find themselves
suddenly plunged into the heart of a
tropical jungle and a veritable wilder
ness of ferocious-looking lions, glower
ing tigers, menacing rhinoceroses and
other wild creatures.
Contrary to the popullr conception nf
* museum as a place where specimens
see assembled, stiffly arranged and then
left merely to collect dust, the great ex
id!e»t«. fuc.. It It
Mbits at the American Museum of
Natural History are constantly being
augmented and presented in the most(
lifelike manner that the science of taxi
dermy ran devise. Thus, as the scientist
and explorer extends his sway over ihe
jungle, the beasts of the jungle find their
way in ajl their natural environment
into the heart of the world’s greatest
city.
Ferocious tigers, for example, are seen
crouched to spring out of the tall jungle
glass upon their unsuspecting prey.
Bold lions impudently stare back at the
visitor and rhinoceroses stand in the
threatening sttitudeof a charge. A look
is • thrill, for the. beasts are surrounded
hv the rorki and foliage of their native
lairs. The effect is startlingly realistic,
in spite of the fact that the animals art
confined in glass cages. v .
Perfect skins of magnificent speci-.
*■ mens of jungle-land, after being chemi
cally treated, were stretched over skil
fully sculptured models of the original
animals. The figures were then placed" O
in lifelike poses in a setting of tree*,
grasses and reeds that were either
brought direct from the jungle or fash- - -
ioned from paintings made on the spot.*
After the figure of each animal fead ’
been completed its fur was carefully
brushed to give it a natural sheen. Even'--• -
the eyebrows of each animal were pen- '
oiled and its claws manicured to add to
its lifelike appearance.