The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-05-09
ny CLEVELAND MOFFETT.

" HE swiftest thing that the hu-
man race has ever put in
motion is the steel projectile
of a I2-inch gun. No human
eye can follow it's flight. Released at
a pressure OF 10000 pounds to the
square inch-in a heat at which dia-
monds melt and other forms OF carbon
boil--it darts through the air at the
rate Of twenty-five miles a minute and
reaches the mark ahead Of its own
sound!
One OF the most progressive
branches Of our military service is the
department of coast defences. which
under the farseeing guidance Of Gen.
+. NJ. Weaver holds our shores and
harbors in a state OF alert prepared
ness against foreign aggression.
At Hampton Roads sits the coast
artillery board, composed Of officers
and consulting engineers to whom are
referred all problems relating to coast
artillery and who have the RESPONSE
bility Of testing all new instruments
proposed for artillery use. The pur-
pose Of this article Is to describe one
among several notable achievements
OF the Hampton Roads Coast Artillery
School. this particular work having
been done by Capt. +. J. Behr of the
Coast Artillery Corps, who after years
Of effort has recently developed a sys-
tenn that makes IL possible to take
pictures OF the swiftest moving bodies,
the great steel projectiles of our big
gest guns-to seize them with the
cameras eye as they hurl through the
air at enormous velocities or at the
very moment of their emergence from
the gun muzzles, and to preserve these
images, never seen before. for mill
tary study and comparison. Capt.
Behr was ably assisted in this work
by Engineer ]. A. Wilson.
Some Of the increments and dec
rements of time involved in the photo
graphs herewith published are as
small as 1-10,000th part of second.
And Capt. Behr has devised a method
Of taking photographs Of projectiles
as they arrive at a steel target and
penetrate the target inch by inch that
involve increments or decrements Of
time as small as the l00, 000th part Of
a second.
To the uninitdated 1T seems in
credible that such infinitesimal d.
visions OF time can be used in prac-
teal calculations, but every trained
phys st knows that in wireless work
scientists OF to-day speak casually Of
experiments that take account OF two
tenths or one-tenth OF a millionth part
Of a second!
What happens to the projectile af-
ter 1t leaves the gun. or after the dis
charge Of the gun and before the pro-
jectile has had time to issue from the
gun barrel? What is the action at the
muzzle OF gases generated?
What shape do these gases assume
as they leave the gun? What causes
the much discussed gas rings" that
sometimes form when a mortar is
fred and oftener do not form? What
phenomena attend the arrival OF the
projectile at a solid steel target? Is
the steel actually fused by the heat OF
impact? Is 1t vaporized? Or what?
These are some OF the questions tina.
Capt. Behr set himself to solve, or 10
help in solving. as he worked out his
methods of rapid photography. His
aims were strictly military. but his
results make fascinating appeal to the
general Imagination. Fancy doing
anything in the one hundred thou
sandth part of second!
Capt Behr's general idea was to uti-
lie some phenomenon connected with
the discharge to actuate, by electrical
connections. n mechanism that would
work a rapid shutter in a properly
placed camera.
The phenomenon OF conclusion was