Omaha daily bee. (Omaha [Neb.]) 187?-1922, 1917-06-11
The Eyes OF War
BIZ Freuerlc j. HdSam

Washington June 8-The Federal Bureau OF
Standards, OF the Department OF Commerce, will
be able to supply the needs of the American army
in the matter of optical glass. This is matter
OF the very highest Importance, and represents
distinct triumph for the bureau in technical
and scientific way. The manufacture OF high
grade lenses is one Of the most complex, delicate
and difficult tasks imaginable. Until the out
break OF the war the highest degree OF pertec-
ton in optical glass was attained only III Ter
man and Austrian factories.
1t was part OF the worlds system OF scien-
tihc production before the war Tor each nation
to specialize along particular lines. thus Ameri-
can instruments OF precision were probably. the
best made anywhere In the field OF optical IN
struments, especially optical glass, Germany and
Austria led, and this leadership gave Germany
an immense advantage in the early days OF the
war. But the last three years have proved that
each nation which makes war must be prepared
The Bureau OF Standards has brought its work
to point where America can meet the exacting
requirements Of the army for optical glass.
Nowhere is the remarkable development Of
finely made glass lenses more beautifully shown
than in the aeroplane camera. These cameras are
literally the eyes of the army Every foot OF the
battle-ground and the territory behind it is photo
graphed scores OF times day. These photo.
graphs are made by men flying 5000 and 10000
feet above the ground level at speed OF eighty
miles an hour or more, and they are as clear
and distinct as the cabinet photo OF ten years ago
Only an expert in optical instruments can APP
preciate the triumph of science represented by
the lenses OF these cameras. A simple lens, which
will make photograph OF sort has no less
than FIVE separate and distinct factors OF error,
and would show nothing but a blur if used under
conditions much less trying than those of aero
plane photography In order to overcome the
sources of error it is necessary to combine
glasses OF different chemical composition in such
way that each glass exactly neutrazes the
error of the others. The composition OF such
glasses must be calculated to the minutest frac-
ton The glasses must be cooled annealed,
ground and polished until they are accurate down
to the finest point that human Instruments can
measure.
Some of the great military cameras in use
on the western front make pictures seventeen
inches by twenty inches. Such cameras nave
lenses with what is known as thirtysix-inch focal
length-that is, the lens is placed yard distant
from the sensitive plate This is necessary III
order that objects on the ground may stand out
from lens to plate the more useful are the photo
graphs from the military point OF view But III
order to combine this long focus with speed, 1t is
necessary for the lens to be very large, and each
increase in size of the lens increases many times
the difficulty of casting and grinding 1t accurately.
The lens on such camera may be as much as
six inches in diameter 1t must be so perfectly
made that this great block of glass, combined OF
different elements, casts sharp clear image OF
the scene below on every part OF the photo
graphic plate.
Most of the aeropane cameras are smaller IN
size than this on account of the difficulty in
handling the big plates. These smaller cameras
take pictures of such sharpness that they may
be enlarged without loss of detail. The weight is
Al,,ks as tha lryaf
cameras weigh as much as 200 pounds. This limits
considerably the height to which the aeroplane
can rise, and exposes the observer to greater
danger from shell-hre. Specially constructed aero
planes are being used to carry these big cameras
equipped with devices to eliminate vibration.
An army photographer may make 30O pic
lures in single aeroplane fight, and there are
hundreds of photographers attached to the aero
plane divisions Of each army. Thus thousands
Of pictures are brought back daily from over the
enemys lines. These pictures, along with what
the observer sees through his field glasses, are
the real basis for military operations.
The signal CORPS of the American army faces
an unusually difficult problem in war photography
in laying its plans for possible deepce OF Ameri-
can territory. This is due to the lack OF military
maps of American soil 1t is comparatively easy
for staff officer who has arge-scale and de-
tailed military map of given region to take a
number OF photographs of that region and bring
the situation up to date from day to day, Lack
ing the large-scale military map, the problem be-
comes more difficult In such case, the map
must literally be drawn from Photographic data.
1t is said that our signal corps and engineer Of
hcers recognizing this problem, have worked out
a most efficient system for mapping new region
entirely from aeroplane photographs. Details OF
this system are, of course, not available, but ii is
said that new apparatus of great value has been
invented and constructed by American experts.
The camera is only one instrument of modern
warfare in which highly perfected optical glass
is the essential factor. Field glasses and tele-
scopc riAe-sights are other common examples.
The Germans had great superiority in these
instruments in the beginning of the war, but the
allies quickly put themselves on an equal footing
The remarkable performance of long-range
naval guns is based on optical instruments of
beautiful delicacy and precision. Naval range
finders are sometimes built more than thirty. feet
long Periscopes as used both on land and sea
are based on the use of high-grade glass, though
the need for great perfection in these instruments
is not so pressing