After the Civil War, as the paradigm of national security shifted from conquest to prevention of loss of life and property, the US Army Signal Corps—still run by Myer—began to perform the work of a national weather service. Among its innovations were daily weather bulletins, telegraphed across the country to be displayed at local post offices, and the daily publication of an international weather map. Scientific collaboration became a key feature of its work. Myer’s successor established the corps’s Scientific and Study Division, sought input from consultants such as Alexander Graham Bell and the astronomer Samuel Langley, and sponsored a textbook on meteorology. The metamorphosis of the corps’s identity and activity from wartime to peacetime is a case study in adaptability.55
Besides becoming the world’s weatherman after the Civil War, the US Army Signal Corps helped launch many other practices that are now integral to military operations: combat photography, airborne radiotelephones, photoreconnaissance and aerial mapping, communications satellites, even (with the help of Wilbur Wright) military flights. During World War I the corps took responsibility for combat and surveillance photography both foreign and domestic, on the ground and in the air, producing tens of thousands of stills and hundreds of thousands of feet of motion pictures.56 As communications historian Joseph W. Slade wrote, by the end of the twentieth century the Signal Corps had turned into “Ma Bell with guns.”57 Telescopes and binoculars, reconnaissance aircraft, bombs, satellites, and telecommunications: the intersection of war and astrophysics is neatly embodied in the corps’s evolving duties.
Speaking of the erstwhile North American telephone conglomerate Ma Bell: during World War I its parent company at the time, AT&T, supplied its chief engineer to the Signal Corps Officers’ Reserve Corps.58 Since then, corporate giants have become integral to every war effort. The envisioning, anticipation, and implementation of war have in fact spawned some of these corporations and multiplied the profits of others. Today there are no standardized armaments without manufacturers, no inventions without patents, no stockpiles without suppliers—global webs of interdependence, benefit, and responsibility. The elimination of a single supplier, the sudden unavailability of a single product, can cripple a country or help shift the course of a war.
Like so many sectors of what is now a global industrial marketplace, the precision optics industry began with a scattering of assiduous, independent-minded individuals. A barrister hobbyist, for instance, working alone in a gentleman’s laboratory in Essex, discovered a major principle of refractive lens design—how to minimize the spurious appearance of color in the image—but sought no recognition for it. He was simply solving an intriguing puzzle for his own pleasure.59
The curve of a lens determines the angle at which the light rays will bend as they pass through it, and thus the distance over which they come to a focus or diverge. If the curve bulges out, like a beer belly, the lens is convex and will bring the rays to a focus. If the curve sinks inward, like a cupped palm, the lens is concave and will force the rays to diverge. If one side is flat and the other curved, the lens is called either plano-convex or plano-concave. And if both sides are curved, you’ve got a double convex or double concave lens.
The color problem in lens optics derives from a simple feature of angled glass. A triangular prism, by design, splits white light into its component colors, with each color emerging from the other side of the prism at a slightly different angle from all the others. A double convex lens—a crucial feature of telescopes—is not very different from two prisms cemented to each other at their base. While it doesn’t produce such extreme coloristic effects as two pure prisms, this lens will focus different colors of light at different distances within the telescope tube, creating unwanted colorful aberrations unless corrective lenses are added to the system. The thicker the double convex lens, the shorter the telescope tube can be, but the more severe the problem becomes. Reflecting telescopes create no such problem, because all colors of light reflect at the same angle.
The beginning of the end for color problems came in 1758, when two things happened. The first was that a mathematically inclined, London-based ex–silk weaver named John Dollond published in Philosophical Transactions an account of his experiments with lens sandwiches formed of two different kinds of glass—crown and flint—which exhibit different refractive qualities. The second was that John Dollond applied for a British patent for his sandwich, calling it the Achromatic Lens, “whereby the errors arising from the different refrangibility of light, as well as those which are produced by the spherical surfaces of the glasses, are perfectly corrected.”60
By rights that patent (of only fourteen years’ duration) should have belonged to the barrister Chester Moor Hall. But he hadn’t sought it, and Dollond had. The following decade, John Dollond’s son Peter added a third lens, eliminating residual aberrations and creating the perfect club sandwich. Never again would a telescope have to be fifty feet long to yield clear, crisp results. Soon the seamen of the Royal Navy began to call a telescope a “dollond,”61 and the progeny of the Dollonds’ dollonds became standard field equipment for warfighters on the move. George Washington and Napoleon alike (not to mention Captain Cook, Frederick the Great, a long list of British royals, the father of Wolfgang Mozart, and untold others) would have been lost without J Dollond & Son or, subsequently, P & J Dollond Instrument Makers, foremost suppliers of a variety of precision optics for most of the eighteenth and much of the nineteenth century.
Neither the Dollonds nor Britain held the field unchallenged. In 1846 a thirty-year-old technologist-optician named Carl Friedrich Zeiss opened a workshop in the small town of Jena, Germany, that soon became the dominant corporate power in the optics industry. And just before the Civil War the American company Alvan Clark & Sons set up shop in Massachusetts. Most American observatories built in the second half of the nineteenth century, when enthusiasm for astronomy was on the rise, relied on one or more of the Clarks’ superbly hand-crafted telescopes, and during the war itself the company sold the US Navy nearly two hundred expensive spyglasses.62
One item required by all manufacturers of precision optics was fine, clear, homogeneous optical glass—blank slabs ready to be ground and polished by exacting craftsmen such as Alvan Clark, who finished them with his bare thumbs rather than resort to an insufficiently soft cloth.63
A material at least as ancient as the pharaohs, glass is made mostly from molten sand, cooled in such a way that it bypasses the crystallization phase. But optical glass is a far cry from the glass used for bottles and beads, and no pharaoh’s workshop could have produced it. Nor, centuries later, was it an easy sideline for the producers of window glass, though some of them made the attempt. As the American astrophysicist Heber D. Curtis wrote at the close of World War I, it is “a substance which differs from ordinary glass almost as much as does the diamond from graphite.”64 (A year later, Curtis would bet on the wrong horse in a highly publicized debate about whether the Milky Way was the entire universe or whether the spiral fuzzy objects seen dotting the night sky were other galaxies, rendering the actual universe vastly larger than previously imagined.)
Quality optical glass requires vast quantities of fuel and highly controllable furnaces. It needs melting pots that won’t contaminate the fiery brew, and it must be stirred well. It needs the right flux to draw out impurities. Bubbles, veins, strains, and cloudy patches must be prevented from forming during cooling. If the goal is to vary the refractive effects in different parts of the spectrum, various substances may be added: lead, barium, boron, sodium, silver, uranium, mercury, arsenic. Above all, optical glass must be utterly transparent and uniform.65
Fine optical glass blanks of a decent size were hard to come by until well into the nineteenth century, and instrument makers paid dearly for them.66 Dollond had come up with a lens design that promised excellent astronomical telescopes, but the promise was infrequently fulfilled. A design is only a recipe. If you don’t have avocados, you can’t make guacamol
e.
For decades, just two companies—Chance Brothers of Birmingham, England, and Parra Mantois et Cie. of Paris—satisfied most of Europe’s appetite for optical glass. In the early 1880s the spotlight switched to Jena, where Carl Zeiss and two university-trained scientists had formed a legendary industrial collaboration. The senior scientist was the physicist Ernst Abbe, who had made major contributions to the mathematics of optics—having determined, for example, that the resolution of a telescope or microscope is limited by the size of the instrument and the wavelength of the light it brings to focus—and was already collaborating with Zeiss in the manufacture of advanced microscopes. The junior scientist was a young PhD chemist named Otto Schott, whose dissertation topic was the fabrication of glass. No longer could trial-and-error craftsmanship suffice. Apprentices now needed the input of academics, and the optician himself attended university lectures whenever he could.
Together these men expanded Carl Zeiss’s already impressive optical workshop and also set up Schott & Associates Glass Technology Laboratory. Shortly after Zeiss’s death in 1888, Abbe formed the Carl Zeiss Foundation, which today owns Carl Zeiss AG and Schott AG and thus is responsible for the awesome star projector—the Zeiss Mark IX—that rises up out of the floor of the Space Theater in New York City’s Hayden Planetarium.67 Among the early Zeiss/Schott corporate conquests were the perfection of low-expansion borosilicate glass (what the rest of us call Pyrex), the apochromatic lens (a significant advance on the achromatic lens, bringing all wavelengths into focus in the same plane), and the mass-produced prismatic binocular. By the eve of World War I, Zeiss was the preferred supplier of most “optical munitions”—one-person observation devices that included binoculars, rangefinders, panoramic artillery sights, and submarine periscopes.68 But Zeiss was producing fine nonmilitary equipment as well: astrophysicists sought its new-generation large refracting telescopes, photographers sought its cameras, all sorts of people sought its microscopes. In June 1914 the many departments of the Zeiss works in Jena employed more than five thousand people.69 (In June 1945, by the way, US occupation forces removed seventy-seven Zeiss scientists and executives from Jena—which sits squarely in Germany’s east—and took them to the southwest, where they set up a Zeiss subsidiary in Oberkochen. Cold War politics intervened in 1953, when the government of East Germany cut off contact between the eastern and western branches. In 1991, soon after Germany’s reunification, Zeiss reunited as well.70)
Despite the many advances made by Zeiss, Abbe, and Schott, size remained a challenge. The curved metallic surface of a reflecting telescope’s polished mirror could not be shaped perfectly. For those who sought ever-larger glass lenses in the nineteenth century, Alvan Clark had seemed a godsend. But the refracting telescope’s glass lens had problems of its own. Hand-and-thumb craftsmanship is hardly mass production, and the continuing paucity of fine optical glass limited the quality of a telescope’s optics. Most important, the sheer weight of a large glass lens, which must be held in place only at its perimeter, posed a severe engineering challenge.
Fortunately for astrophysicists, the germ of a better solution was already available. In 1835 the German chemist Justus von Liebig had introduced the silvered-glass mirror. Made by depositing a thin layer of silver vapor on one side of a slab of polished glass, it offered an excellent image and soon became a fixture of every bourgeois household. Two decades later, Jean-Bernard-Léon Foucault (the pendulum fellow), in collaboration with the Paris Observatory’s official optician, improved upon this technique by adding a subsequent phase: localized repolishing to correct errors of form. This enabled Foucault to make ever-larger reflecting telescopes, culminating in an eighty-centimeter telescope installed in the Marseille Observatory in 1864.71
Today the largest telescopes in the world are all reflectors, and all of them use a mirror with a vapor-deposited metal coating on one polished glass surface. While the lens of the largest extant refracting telescope is one meter across, the mirror of the largest reflecting telescope is more than ten meters across. Others in the works approach forty meters in diameter. Hardly anything limits the size of the mirror, because it is mounted from the back. As a result, since the end of the nineteenth century, the reflector has been the astrophysicist’s instrument of choice.
The military solution, however, lay elsewhere. For nearly the entire nineteenth century, military planners and artillerymen alike fretted far less than astronomers about the limited availability of fine optical glass. An infantry rifle that could be fired effectively at a target more than a mile away was not yet on the market.72 Gunners did not rely on barrel-mounted spotting scopes. Civil War cannons were fired point blank in the general direction of a nearby visible enemy; battling Northerners and Southerners estimated distances strictly by eye and aimed their guns with the aid of spirit levels and plumb lines, hoping to overwhelm the enemy with a barrage of shot. “The gunners sighted their fieldpieces hastily and banged away, trusting to hit some vital spot,” writes Lieutenant Colonel F. E. Wright in a historical overview produced in 1921 for the Ordnance Department of the US Army.
By 1914, gunners equipped with optical munitions were able to attack unseen targets fifty thousand yards away, targets whose positions had been calculated on a map. Optical aids had become indispensable. The gunner who lacked them, says the colonel, “is almost helpless in the presence of the enemy; he can not see to aim properly . . . and his firing serves little purpose.” The manufacture of optical glass had become “a singularly important key industry.”73 Writing in 1919, Heber Curtis was equally forceful: “When we pass from the needs of peace to the requirements of a nation waging modern scientific war, optical glass changes from a mere essential of the observatory or the laboratory to an element nearly as indispensable as the high explosive.” Or, to use a phrase of economic historian Stephen Sambrook, “no gunnery without glass.”74
So, you might think that by the eve of World War I, every Western nation-state with an industrial base and a habit of waging war would have funded the building of factories to make their very own optical glass and optical munitions, that they would have stockpiled raw materials, fuel, and finished products, ensured an adequate workforce of skilled personnel, and signed the treaties that would guarantee a steady supply of optics to their armies and navies. But no. They hadn’t.
Among their other failings, key countries of the Entente now relied heavily on a single factory for a great deal of their optical glass: Schott & Associates Glass Technology Laboratory, located well within the borders of what was soon to become enemy territory.75 The UK was Schott’s top importer of optical glass; the USA was second.76 The details of Schott’s manufacture were proprietary information. Despite the recent spate of wars and despite warnings from informed individuals,77 the West’s large nation-states—whose kings and parliaments had for four centuries been putting 30 or 50 or sometimes 70 percent of their annual budgets into war and armaments78—had directed inadequate attention and money toward securing local production during wartime.
Inevitably, crunch time came.
Suddenly countries were scrambling to fill urgent needs, not only for optics but also for photographic chemicals, pharmaceuticals, synthetic dyes, high explosives—much of which had previously been imported from Germany, duty free. Nor was the cutoff of imports the only difficulty. Vast armies, new industries, new materials, and new practices had to be created almost from scratch. The war effort required bombs, mass-produced vacuum tubes, carrier pigeons, ammonia, pilots’ clothing, unprecedented numbers of airplane motors, the airplanes themselves. From 1903 through 1916 a mere thousand planes, none intended for combat, had been built in the United States, and yet in late May 1917 the US government was asked to come up with two thousand planes and four thousand engines a month, as well as five thousand pilots and fifty thousand mechanics within a year.79 Near-instantaneous demand for optical glass and optical munitions reached comparable levels. The only solution was intensive cooperation among industrialists, sc
ientists, diplomats, patent lawyers, military brass, procurement officers, and the factory floor.
As for Britain, the military’s prewar demands could be satisfied by a few flourishing British manufacturers. The Royal Navy had been a patron of homegrown precision optics companies since the 1890s, followed within a decade by the British Army. Barr and Stroud Ltd, which started in 1888 as a casual collaboration between a professor of engineering and a professor of physics, had by 1897 become the world’s sole manufacturer of rangefinders. Soon it was supplying them to Japan and every major European power except Germany. Between 1903 and 1914 it pulled in £750,000 in foreign contracts and £450,000 in Royal Navy and War Office contracts.80
But with the onset of war, existing channels of glass supply had to be realigned or relinquished. Three British optical-munitions manufacturers, specializing in three different instruments, had become almost entirely dependent on French-supplied glass. Starting in 1909, Chance Brothers of Birmingham, primarily a maker of window glass, had been investigating the secrets of making the optical varieties, and in August 1914 its monthly output was a thousand pounds of the good stuff. Not even close to enough. Within a year, the War Office required a monthly output of seventeen thousand pounds, and British glassmakers were being hamstrung by their dependence on imported raw materials, some of which came from—you guessed it—Germany.
In mid-1915 Chance Brothers and the Optical Munitions and Glassware Department of the Ministry of Munitions (whose first director was a lecturer in physics, an expert on optics generally and rangefinders specifically, and a former Examiner of Patents, thus embodying the modern alliance of science and war with industry) finally agreed on the terms of a public–private partnership.81 The government would supply money and procure scientific input, and Chance would maintain adequate facilities and personnel and would achieve specified outputs; after the war, Chance would become a monopoly supplier to the military but could continue to use the facility for ordinary commercial production. It was a win-win situation. By war’s end, the company was producing more than ten tons—comprising seventy different types—of optical glass a month.82
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