Measures for Progress: A History of the National Bureau of Standards

418 WORLD WAR I! RESEARCH (1941-45)
An assortment of optical glass specimens made at the Bureau. Center bottom is a co-
incidence prism used in range finders. One o/the most intricate and costly of optical
devices, it was made at the Bureau by cementing together a number of small prisms.
Of the services, the Navy was the great consumer. A single big rangefinder
for one of its guns contained as many as 160 optical elements.
Altogether, the Bureau furnished close to a million pounds of high.
quality optical glass to the Armed Forces. Where the Bureau previously
made no more than six types of optical glass, military and research require-
ments called for 28 types before the war ended. At peak production 400
workers under Alfred N. Finn and Clarence H. Hahner were employed around
the clock, not only to produce the glass but to mold it into prisms and lenses
for readier use in gunsights, heightfinders, periscopes, rangefinders, and
binoculars.148
In the optics division (optical glass was a product of the ceramics
division), investigations were carried out on improved rangefinders, in meth-
ods and instruments for testing airplane cameras and lenses, and in optical
measurements and materials for camouflaging ships and shore installations.
Assistance was also furnished the Navy Bureau of Aeronautics in the design
of special aircraft searchlights for use in night attacks on submarines, and in
photoelectric equipment for night photography.
A simple yet new and vitally important device that came out of the
optics division was the heliographic signaling mirror or "solar searchlight,"
"8Hearings * * * 1943 (Jan 12, 1942), P. 208; Hearings * * * 1945 (Jan 11, 1944),
p. 189; C469, "Optical glass at the NBS" (Glaze and Hahner, 1948); NBS War Re-
search, pp. 99—101.