The Perfect Machine

by Ronald Florence

  Formally, the grant from the International Education Board was vested in an Observatory Council consisting of Hale, Millikan, Robinson, and Noyes, with John Anderson, an excellent optician and physicist from Mount Wilson, as executive officer. Although only Hale was an astronomer, Millikan and Noyes were the other members of Caltech’s Big Three, the men who had been credited with attracting the faculty and funds to the small school. Henry Robinson was a member de facto as the chairman of the trustees of the California Institute. Caltech would pay one-half of Anderson’s salary from the grant funds in return for his handling the day-to-day administration of the project.

  An advisory committee was appointed to provide a forum for Hubble and the other astronomers. The Observatory Council and the Advisory Committee both met regularly, but the bulk of the work in these early days fell to Anderson, Hale, and the staff that they assembled. To the world George Hale was the man who built big telescopes. Long after it was announced that John Anderson was executive officer of the project, a disproportionate amount of mail and queries were directed to George Hale. Contractors, bidders, job seekers, reporters, publicity seekers with crackpot ideas, and the curious public all sought George Hale. To the extent his energies and the demons allowed, Hale assumed command from his headquarters in his solar laboratory, firing off endless memoranda, letters, and telegrams. His early influence on the biggest decisions for the telescope—design staff, sitting, and technology—put his firm imprint on the project.

  The first appointment was easy. Francis Pease of the Mount Wilson staff, who had designed much of the one-hundred-inch telescope and whose preliminary drawings and model of the three-hundred-inch telescope had been bantered around for years, was named Associate in Optics and Instrument Design. Pease had taken shop courses at the Armour Institute of Technology in Chicago as a young man, and that introduction to machines and mechanics, together with his training in astronomy and observational experience, gave him an ideal background as a telescope designer. He had been working on sketches and models of a big telescope for so long, and had shared his ideas with so many individuals, both staff at Mount Wilson and visitors, that his preliminary designs became the points of departure for the project. From the beginning Pease was pressured from both sides. The engineers considered him too much the astronomer, lacking the nuts-and-bolts problem-solving mentality of an engineer. To the working astronomers Pease was an astronomer manqué, who was now spending most of his time on machine design rather than research.

  Hale was convinced that the new telescope was such a leap in scale that any design based on earlier telescopes and earlier technology wouldn’t do the job. As a counterweight to Pease, he reached out for an inspired if unlikely choice for a second designer. Hale had been friendly for a long time with Albert Ingalls, of Scientific American magazine. One of the most popular features Ingalls had introduced to the magazine was a series of articles on amateur telescope making, written and illustrated by Russell W. Porter of Springfield, Vermont. Porter was a machine designer, an avid amateur astronomer and telescope maker, and a superb illustrator. His amateur telescope-building articles, later collected in a book, were so popular that Porter became a regular monthly columnist of the magazine.

  Russell Porter had a background most employers would dismiss as too eccentric to trust. As a young man he abandoned his studies of civil engineering and architecture at MIT to sign up as an illustrator and surveyor on an arctic expedition. In the early years of the twentieth century, expeditions to the North and South Poles—then the great unknown for explorers—were much celebrated in the press. For all the publicity, there were often places available on the expeditions, because most men who had tried the arctic once couldn’t bear to go back. Except Russell Porter. He found the stark landscape irresistible. He went back again and again, whenever an expedition could find room for him. He was attacked by a polar bear, had his gun freeze in his hands, got frostbite on four fingers when his mitten came off, and learned the threat of snow blindness to an artist. His duties on one expedition included observations with a Repsold Circle, an instrument designed to measure altitude and azimuth within four seconds of arc. The experience got him used to observing in conditions that made even the most rigorous observatory run seem luxurious: cold of-30° F, working barehanded because the instrument was too delicate to manipulate with gloved fingers. Often his hands were too cold to hold a drawing pencil, and once the kerosene in his lamp froze to a slush. By the age of thirty-four, Porter had completed nine arctic trips and an attempt on Mount McKinley. He had become partially deaf from continued exposure to the cold.

  When he finally abandoned arctic exploration, Porter tried his hand at architecture, then settled down to work for the Jones and Lampson Machine Company in his hometown of Springfield, Vermont. The president of the company, James Hartness, an ex-governor of Vermont, an old friend, and an amateur astronomer, recognized Porter’s genius for simple, functional designs and got him interested in telescopes. Before long Porter’s ability to render complex machines in pencil and charcoal drawings found a focus on telescopes, particularly instruments that could be constructed by an amateur. A series of innovative instruments of his design were built by members of the Springfield Telescope Makers. The group’s observatory, Stellafane, which Porter also designed, became a mecca for amateur astronomers and telescope makers.

  Hale was always on the lookout for people who knew something about telescopes, and by 1927 Porter and Hale were corresponding. Porter wrote an article for Hale’s Astrophysical Journal on using photographs of knife-edge shadows for optical tests, and Hale sent him the plans for a spectroheliograph designed for amateur construction. Hale was impressed by Porter’s designs and drawing skill. Early in 1928 he got Albert Ingalls to set up a dinner in New York for the three of them. Porter’s hearing difficulties made him a poor listener; he compensated by talking throughout the meal, drawing sketches to illustrate one concept or another on any available piece of paper, including the menu and napkins. Hale was impressed.

  Late in the summer of 1928, Hale wrote Ingalls to ask if he thought Porter would come to work on the two-hundred-inch telescope for a year for $3,500 to $4,000. Ingalls said it was hard to guess about a man like Porter, so Hale sent Anderson and Francis Pease to Vermont, to find Porter and feel him out.

  Porter was off on an all-day picnic when the two men from California arrived at the Hartness plant in Springfield. James Hartness entertained the visiting dignitaries, giving them a hard sell on Porter’s talents. Porter finally showed up in his old Ford and was sent in to talk to the two men. No one let him know who they were, and Porter as usual did more talking than listening. When Pease and Anderson managed to squeeze in enough words to explain that they had already missed several trains, Porter offered to drive them to the station, talking nonstop the whole way about the picnic, the virtues of Vermont, the glories of the arctic, the iniquities of the expedition leaders, and the limitations of being an artist. It took a half hour before Anderson was able to ask Porter if he knew anything about astronomy. “Not a great deal,” Porter shouted. “It’s a big subject. Some other time I’ll be glad to tell you what little I do know, though.”

  Anderson and Pease were on their train, ready to depart, when they finally told Porter that they had come to offer him a job working on the two-hundred-inch telescope. For the first time that afternoon Porter was speechless.

  Russell Porter had never worked professionally on a telescope, and never on an instrument larger than an amateur could build. He was fifty-six years old and settled in his ways. It took a lengthy exchange of telegrams before he agreed to come to Pasadena at the generous salary of six hundred dollars per month. It was to be a temporary stay, only until July 1929, so Hale urged him not to bring household goods but to plan on renting a house. Porter’s job was deliberately described loosely: He was to help in designing the two-hundred-inch telescope, various auxiliary instruments, and the buildings to house them.

  Like other employees o
f the project, Porter was put on the payroll of the California Institute. Porter, who had never gotten a degree in engineering or architecture, was an odd appointment for the new school, which had widely publicized the credentials of the distinguished scholars who had accepted early appointments. The engineers and physicists called him “the old guy,” wondering who he was and why he was there. Soon the old guy was drawing architectural sketches for an astrophysics laboratory and machine shops for the campus of the California Institute. He had a unique style, using charcoal and careful smudges with his fingers to provide the “atmosphere” of big machines to his pencil sketches and renderings. Porter drawings were soon a familiar sight on the walls of the temporary buildings on California Street.

  Even with Pease and Porter working full-time on the project, Anderson had his hands full. The heart of the telescope, the two-hundred-inch mirror, was his responsibility.

  Stripped to its essentials, an astronomical telescope is a few grams of silver or aluminum, the reflecting surface that gathers and focuses the faint light of distant objects. Everything else—the precisely ground base of the mirror, the immense mounting, the electrical and mechanical controls, the instruments and cameras, the huge dome, the auxiliary optics—are only there to position and support the reflective surface of the mirror, to protect the instrument when it is not in use, or to enhance the image focused by the mirror. The crucial question for the two-hundred-inch-telescope project was whether a fine-enough mirror could be built.

  The skeptics were convinced that it couldn’t be done. The Bureau of Standards, the federal agency for science, had already pronounced that a telescope larger than the one-hundred-inch was a technical impossibility. The bureau’s opinion carried some authority, because they had cast the first large glass disk ever poured in the United States, a sixty-nine-inch, three-thousand-pound blank for the Perkins Observatory at Ohio Wesleyan University. They had good evidence to support their claims.

  “It is an open secret,” the New York Herald Tribune wrote in 1928, “That the 100-inch reflector at Mount Wilson, now the world’s largest telescope, has been something of a disappointment.” There had been constant rumors of troubles with the one-hundred-inch telescope. Astronomers with grievances real or imagined against the Mount Wilson Observatory, including Harlow Shapley, who feared that money committed to the Pasadena observatories would not be available for the Harvard College Observatory, did their best to exploit the rumors. Shapley would tell anyone who would listen about the woes of the Mount Wilson telescope, including gossips like H. L. Mencken, who could be counted on to spread the bad news without checking it. What non-astronomer would question the judgment of the director of the Harvard College Observatory?

  George Ritchey, fired from Mount Wilson at the end of the war, had gone to his lemon farm in Azuza, then to France, where, with the backing of a wealthy engineer, Assan Farid Dina, he was going to build a 104-inch telescope. The telescope project foundered, but in a series of published articles, Ritchey recounted the history of American telescope building, with himself as hero and Walter Adams and George Hale conspicuously missing. Privately he wrote scathing notes about the “wealth and power and egotism” of the officials at Mount Wilson, and rarely missed an opportunity to criticize the design of the one-hundred-inch telescope.

  The mirror of the one-hundred-inch Hooker telescope was temperamental. Often, for much or all of an otherwise excellent night, the telescope would be unusable or marginal. The best explanation anyone could offer was that the great mass of plate glass was slow to adjust to changes in ambient temperature. The Mount Wilson opticians and astronomers fiddled with the mirror constantly. They tried packing the mirror cell with insulation, different cycles of opening and closing the dome to control the temperature inside, retuning the mirror supports, even removing the mirror during the day and storing it in a cork-lined cell until night. Some of the experiments helped, and the telescope was used effectively by Hubble, Humason, and others. But despite the constant attention, the one-hundred-inch didn’t perform quite as they had expected. Hale and the Mount Wilson staff did their best to keep the bad news quiet, not only as a potential embarrassment but because it was powerful evidence for the skeptics who had already begun sniping at the two-hundred-inch project.

  Everyone agreed from the start that the repeated frustrations in the efforts to cast the disk for the one-hundred-inch telescope were convincing evidence that it would be impossible to cast a larger disk of plate glass. Even if a two-hundred-inch mirror could be cast, the best estimates were that a mass of plate glass that huge might require several decades to anneal. The only answer to the troubles with the one-hundred-inch mirror, which seemed to be caused by the relatively high coefficient of expansion of plate glass, would be a new material. But what? The earliest reflecting telescopes, like Newton’s instruments or the huge telescope Lord Rosse had made, had mirrors made of speculum, a bright metal alloy of copper and tin. Speculum couldn’t be figured to the fine optical surface that modern standards required; it was even more sensitive to changes in temperature than plate glass; after a fresh polish the metal surface reflected only 70 percent of the light that hit the mirror; and every time the mirror was polished enough material was removed to effectively refigure the shape. No recent large telescope mirror had been made from any material other than plate glass.

  Early in 1928 Hale had John Anderson draw up a memorandum on the qualities needed for a large astronomical mirror. The material used, Anderson wrote, had to be shapable into the form of a surface of revolution—paraboloidal, hyperboloidal, or plane—the exact geometry to be chosen contingent on the final optical design of the telescope. Because in use the reflecting surface would be exposed to the air, the heat exchange between the air and the mirror had to set up minimal mechanical forces that would tend to distort the mirror from its optical shape. Finally the disk had to be rigid enough to enable it to be supported in all positions without any appreciable change of shape.

  The only materials that would meet the first requirement were glass or other “hard transparent substances,” or certain metals or alloys, such as speculum, Magnalite, or chromium. Common metals, such as iron, nickel, aluminum, or silver were impossible to polish to an optical figure, because burnishing metal to a high polish would remove enough material to alter the optical shape. There had been some experiments that had achieved an acceptable optical surface on copper, gold, and tin, but never on pieces larger than two inches square, at exorbitant costs, and with the problem that the materials changed shape dramatically with changes in temperature.

  Still the experiments went on. The Philips Lamp Works in Eindhoven, the Netherlands, had fabricated surfaces of glass fused to a chrome-iron backing. The problem with this approach was that if the coefficient of expansion of the backing were different from that of the glass, a change in temperature would introduce strains that would ultimately distort the surface.

  That left glass or another transparent material. The surface of a glass mirror would ultimately be coated with a film of silver or another reflective material a few molecules thick, so the actual transparency of the material was not important, although it did have the advantage of allowing the opticians to check for internal strains in the disk. Ordinary plate glass was out; from the experience of the one-hundred-inch telescope, it was clear that there was no way it could be made to work on a mirror of even greater mass. The search was for an alternate glass or glasslike material.

  George Hale knew exactly where to look.

  Elihu Thomson was one of those inventor-scientists who found a natural home at the General Electric Company. Next to Thomas Edison, he was the greatest inventor in the company’s history, with close to seven hundred patents for electric welding, transformers, centrifuge cream separators, three-phase AC windings, load regulators, magnetic switches, carbon-brush motors, electric-usage meters, electric refrigeration, and control circuits that made electric traction for trolleys possible. His company, Thomson-Houston, had merged
with Edison’s company to form General Electric, and his inventions earned a fortune for GE. In return the company provided generous compensation and built him a substantial research laboratory in West Lynn, near his Swampscott, Massachusetts, home. So much of what he tried ultimately proved successful for the company that GE gave Thomson virtually free rein to pursue his own directions in research.

  Among his many interests, Thomson was an avid amateur astronomer. When he was thirteen, his mother had taken him to see a celestial display of meteors and comets; he later experimented with magnifiers that he sold to his friends, and before long he was inventing optical grinding and polishing procedures. Some historians give him credit for discovering that by rotating one flat glass disk over another, with abrasive between the surfaces, a spherical concave shape is produced in the lower disk—the essential procedure for figuring telescope mirrors. His private observatory at his home in Swampscott was as large and well equipped as the facilities at many universities.

  Thomson’s own telescope was a refractor he built from glass disks cast by the Paris firm of Mantois, but he understood the problems of mirrors for large telescopes. In 1899 he began experimenting with mirrors in the carriage house of his estate. He started with small concave mirrors, too crude to use in a working telescope. Thomson would focus the image of an artificial star (a point source of light) on two mirrors, one of glass and the other of fused quartz, then compare the focused images as he heated the backs of the mirrors with a flame. The heat would quickly distort a glass mirror, scattering the image. With the quartz mirror it took a considerable period of heating before the image was distorted. Quartz, Thomson concluded, could be an ideal mirror material: If a mirror could hold its figure under the heat of a torch, it would be all but immune to the effects of changes in the ambient temperature at an observatory.