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

OPTICAL GLASS AND OPTICAL INSTRUMENTS 187
Stratton had long expressed concern over the foreign monopoly in
high-grade optical glass and the fact that this country had to import every
quality optical instrument it used. Because the glass for the optical systems
of telescopes, microscopes, field glasses, navigation and surveying instru-
ments, cameras and similar instruments was expensive to make and the
market limited, American optical firms imported their quality glass and con-
lined their manufacturing to spectacle zlass, a product midway between
optical and plate glass.68 They had made little effort to learn for them-
selves German formulas and techniques and were content to have high-grade
instruments manufactured abroad.69 The war in Europe abruptly cut off
the supply of both optical instruments and optical glass.
In the fall of 1914 Stratton ordered furnaces and apparatus for the
Pittsburgh laboratory, where investigation of American clays and ceramics
was already going on, and set it to work studying the manufacture of optical
glass. A year later the Bureau began supplying its data to experimental
optical glass plants organized at Bausch & Lomb, Keuffel & Esser, Pittsburgh
Plate Glass and other firms that had been urged to take on this work. But
development of good optical glass was a slow process, artisans in precision
grinding were hard to find, and few outside the Bureau seemed to sense the
emergency. When America entered the war in 1917 the industry had pro-
gressed little beyond the experimental stage.7° In desperation, urgent appeals
went out across the Nation begging private owners to lend their binoculars
and field glasses, in whatever condition, to our military services.
Optical glass, a mixture of silica and chemicals melted in a clay pot,
was highly susceptible to contamination from deterioration of the pot mate-
rial under high heat. The initial problem of the Bureau was to find a suitable
mixture of American clays as pot materials, capable of resisting the corrosive
effect of fluid optical glass. The first satisfactory pot made was based on a
OR
Spectacle glass came under scrutiny during the war, too, when the cost of eyeglasses
skyrocketed. Secretary of War Newton D. Baker complained to Commerce, and Stratton
was asked to investigate. The war had "nothing to do with the increase in prices," the
manufacturers told Stratton. Their price on lenses was a few cents each and they had
increased it less than 10 percent. But the jobbers had raised their profit by 25 to 33%
percent and retailers by 200 to 500 percent. Letter, Secretary of Commerce to Secretary
of War, July 18, 1918, and attached correspondence (NBS Box 14, IPO).
Quality optical glass, unlike glass for electric light bulbs, bottles, and window panes,
must have a high degree of chemical homogeneity, freedom from physical imperfections,
and be of varied compositions to insure a wide range of refractive index and dispersion.
For its prewar status, see Science, 41, 788 (1915) ; George W. Morey, The Properties
of Glass (New York; Reinhold, 1938), p. 26; Samuel R. Scholes, Modern Glass
Practice (Chicago: Industrial Publications, 1946), p. 59.
Robert M. Yerkes, ed., The New World of Science, p. 108; Secretary of Commerce
correspondence, 1917, NARG 40, file 67009/43; MS, "Development of optical glass at
the Bureau of Standards" (NBS Box 4.82, PA).