The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-05-09
Some of the Things Uncle Sans Coast
Defence Experts Have Learned
With Aid of the Camera

trleu UfSt-tne SMASH OI air against
a little swinging door; but this was
much too slow. The projectile was
hundreds OF yards away before the
camera had registered its picture. And
that chance was gone!
In the next trial. several months
later, Capt. Behr arranged to have
the electrical connections made or
broken by the movement OF the gun
carriage itself in recoiling; but the re-
suit was unsatisfactory.
Nor was he more fortunate at the
succeeding target practice, when, hav-
ing placed the apparatus further for
ward on the parapet, he had the cam
era demolished by the force OF the
conclusion and several blades OF the
rapid shutter broken.
He was satisfied now that his effort
to actuate the camera mechanism from
the gun carriage would never give the
requisite precision in results, and he
saw that he must work with a device
functioning more reliably.
In the months that followed before
the next target practice The Captain
did some experimenting and finally de-
termined making the projectile itself
displace a length OF piano wire fixed
across the muzzle Of the gun and thus
actuate the electrical system and OPP
crate the shutter.
In this way he eliminated trouble
some variables OF recoil, elasti of
the carriage, &C., leaving to determine
only the time element of the electrical
system to function.
This result was admirable and after
taking several similar pictures the
Captain found that he could now OPP
crate with great precision-that is,
he could get the same phase OF the
discharge with almost Identical shapes
of gas cone and smoke cloud and he
could get these every time.
In the fall of 1912 Capt. Behr sue
ceeded in obtaining series Of ex-
tremely rapid photographs showing a
IL inch mortar battery in action. In
taking these pictures the camera was
placed on an elevation about ten feet
above the concrete floor and about
sixty feet back Of the mortars. The
electrical device for working the shut
ter was actuated by the mortar itself
in its recoil These pictures were
taken in about one five thousandth Of
a second.
SO great was the precision OF the
electrical device as to render possible
the Photographic recording OF these
mortar projectiles. moving at great
velocities. in almost any desired posi-
ton after the discharge. say two feet
away from the muzzle. or six feet
away, or twenty feet away. or right
at the muzzle.
1t is interesting to note that the
strange "powder-puff" effect is never
seen, and although the crashing ex-
plosion has taken place and the pro-
jectile is already started on It's long
journey. the men (even the lanyard
man. who IL nearest) have heard moth
ing. since the sound waves have not
yet had time to reach their ears. Nor
has the mortar itself had time to recoil,
as it does presently. down into the
well in the floor OF the pit.
The men aboard the towing vessels
that drag the floating targets during
gun and mortar practice would seem
to be in a dangerous position, since
the tow line is not more than 200
yards long for guns and 500 yards for
mortars, and a very slight error in aim
or adjustment might cause deviation
of several hundred yards when the
range is eight or ten thousand yards.
AS a matter Of fact, such errors do
not occur. and gun pointer who
would make a right or left deviation
from me target Of ten yards or at the
most fifteen yards. at distance OF
five miles, would be considered unfit
for his job.