The Perfect Machine (23 page)

Spraying the surfaces of the disks by hand wouldn’t work. What Ellis needed was an apparatus that would hold the spraying equipment a constant distance from the molded blank and move it over the surface of the blank uniformly and at a constant speed. He had the lab
shop fabricate a burner and piping to carry the fuel, oxidizer, and powdered quartz. The metallurgists experimented until they found a nickel alloy that would work in the nozzle of the burner. To keep the brass of the oxygen and hydrogen pipes, and the burner itself, from melting in the intense heat of the furnace, Ellis added more pipes to his apparatus for cooling water, until the device began to take on the appearance of a Rube Goldberg drawing.

After months of tinkering he had the workmen fire the gas furnace to spray another disk. The process seemed to work, but the disk emerged from the furnace with the surface pocked with bubbles. It took weeks of sleuthing before Ellis traced the bubbles to iron particles and porcelain contamination in the supposedly pure quartz. More detective work identified the culprit as the ball mill that had been used to crush the raw quartz to a flourlike powder. The pages of the project calendar began turning by months instead of weeks.

Ellis confidently reported that the problems were isolated and fixable, but by the end of 1928, he and his staff still hadn’t produced a mirror blank that could be ground to an optical surface. In Pasadena the opticians were impatient for disks to grind. Pease and Porter needed to know whether the mirrors could be cast before they went ahead with design plans. Hale and the Observatory Council needed to know whether they could build the telescope they had promised.

While he waited for the ball mill to be rebuilt, Ellis designed a new mechanical support capable of moving three burners together inside the furnace. The new apparatus was installed in the large furnace, and everything was readied to attempt a second eleven-inch disk. The machinery they were using for this disk, Ellis reported to Pasadena, could be scaled up to build mirror disks large enough for use in the telescope, at least as auxiliary mirrors.

When everything was finally in place to fire the electric furnace, one of the three workmen trained in the use of the burners sprained his back and was laid up for a week. As soon as the man recovered and returned to the lab, he and his assistants got the flu. Two more weeks were lost. The project seemed cursed.

Finally, at the beginning of the new year, Ellis fired the large furnace. The roar of the oxyhydrogen burners was deafening. Through the peepholes, the inside of the furnace glowed an intense, hellish yellow. The process consumed tank cars of hydrogen and oxygen at a ferocious rate as the layers of quartz were slowly fused onto the base of the disk. After seventy-two hours of continuous spraying, during which he had gotten little sleep, Ellis realized that the coating was being deposited unevenly, with lumps of fused quartz in some areas and bald spots in others.

He tried to adjust the flow to the three individual spray burners, but the only way he could reset the valves was temporarily to stop all work, partially cool the furnace, relieve the vacuum inside, and finally
lift the cover of the furnace enough so the workmen could get to the equipment inside. After adjustments the furnace was resealed and fired, and the entire crew waited until the pumps drew down a vacuum before they could begin spraying again. Even the most cynical pessimists hadn’t predicted the process would be this complex or slow.

The only aspect of the program that was ahead of schedule was the billing. Every piece of new equipment, each delay, and each breakdown increased the cost. When Anderson asked about the huge bills that Ellis was sending to Pasadena, Ellis provided detailed breakdowns, documenting every cent. The lab equipment, all experimental and specially fabricated for this job, was expensive. The process needed lots of men and huge quantities of fuel and supplies. The original agreement with GE, made in the summer of 1928, had been for one year of work. Six months had gone by, expenditures were already approaching the figure projected for the entire series of mirrors, including the two-hundred-inch mirror, and Ellis still hadn’t shipped a mirror that could be used in a telescope.

Another month passed before Ellis finished a second eleven-inch disk. It was the first complete test run of the molding and surfacing process they hoped to use for the production of telescope mirrors. When the furnace cooled and the workmen lifted the cover, they found that the surface of the disk had cracked, probably from the repeated thermal shocks when the furnace had been partially cooled to service the burners. Despite the bad news, Ellis and Thomson hadn’t lost confidence: “We have not encountered any serious obstacle,” Ellis wrote to Anderson, “and are convinced that the production of the large mirror is merely an engineering problem.”

The word “merely” troubled Anderson. Eager to see the promised progress, he visited the West Lynn laboratory. Ellis put on a good show but admitted that there were still enough problems with the spray process that he thought they should hold off on building a larger furnace and the associated spraying equipment, and assigning the additional men to the project, until all the problems were worked out with smaller mirrors.

In the midst of the bad news, Professor Thomson proposed a new idea. Instead of fabricating massive, solid mirror disks for the telescope, he suggested that they could rib the backs of the mirrors, like giant waffles. The ribbing would reduce the weight of the mirror while still maintaining the rigidity, and the pockets in the back would provide a means for supporting the mirror in the telescope. The arrangement, he assured Anderson, would be easy with quartz, though “practically out of the question for glass.” Anderson liked the idea, and Thomson agreed that as soon as the spraying experiments were under control, the laboratory would produce a proposal for ribbed backs on the mirrors.

Thomson’s ribs were an appealing idea. The whole project was
filled with appealing ideas. Back in Pasadena they were beginning to worry when they would see a mirror for the telescope. The pessimists wondered
if
they would ever see one.

In Europe, Hale was supposed to be resting, away from the fray and the demons. But he was obsessed with the telescope. Against the orders of his physician, and from seven thousand miles away, he insisted on regular progress reports. When Anderson and Pease scheduled a trip to the East Coast, Hale sent a list of people they should see, obscure German publications on optics they should research in the New York Public Library, and questions they should pose to experts, consultants, possible subcontractors—anyone who might be useful to the project. He wanted them to ask the Zeiss people about the counterweight schemes they had used on some of their recent telescopes. He had questions for Gano Dunn and Elmer Sperry, of gyroscope fame, about bearings and mounting designs. H. H. Timken, the famed roller-bearing builder, was to be asked whether roller bearings could support the enormous weight of a two-hundred-inch telescope, and Hale wanted them to research the new low-heat-coefficient alloy Invar for possible use in the telescope tube.

Hale had appointed committees for every aspect of the telescope project. Anderson chaired the Committees on Site, Optical Design and Mirror Discs, Bolometric Apparatus, Design of 200-inch Telescope Mounting, Laboratory Design, and Design of Instrument and Optical Shops. The members included astronomers, engineers, and other scientists from Caltech, the Mount Wilson Observatory, and outside organizations like Warner & Swasey and GE. Dozens of astronomers, engineers, opticians, and others—including Harlow Shapley—were listed as official consultants to the project. Each committee theoretically had the authority to consider all options and to make recommendations. On paper the project was reaching everywhere, soliciting and combining opinions from the widest range of sources.

In fact many of the members of the committees served in name only, and many committees existed mostly on paper. The Committee on Optical Design and Mirror Discs was responsible for the big decisions about the mirror, the heart of the telescope. Their charter from George Hale requested that they

begin immediately a theoretical and experimental study of the various possible forms of mirror discs (solid, superposed plates fused or cemented together, two plates
fused
to an intervening cellular structure, ribbed, etc.), and the efficiency of existing systems and new systems of supporting them in all positions they must take in the telescope.

It was an expansive charter, but the order for the mirrors had already gone out to GE a year before. Anderson briefly explored the idea of
mirrors of metal coated with glass, and Sir Charles Parsons in England received a query about his plans for hollow disks, but neither investigation went beyond a few letters and a sample of the proposed disk material. The design criteria Hale sent to the Committee on Design of 200-inch Telescope Mounting were based on “the assumption that the weight of the mirror disc will be that of solid fused silica.”

The committees met from time to time, but most of the decisions on the telescope emerged in notes and memoranda from George Hale. Despite his health problems, he kept his fingers in every pie. Hale asked for answers to his queries in writing, on notebook-sized graph paper that he could insert into the binders he accumulated in his study at the solar laboratory. On Anderson’s own copy of the memo setting up committees, Hale had his secretary, Miss Gianetti, type special requests:

Dr. Anderson:

Please allow for the use of a 60-inch mirror on each side of the 200-inch tube, one for solar work (projecting far enough to permit the 200-inch tube to be completely shielded from sunlight) and one for stellar work. Both to be suitable for photographing in the ultra-violet.

      G.E.H.

The requests and suggestions of the man who had almost single-handedly shepherded the three largest telescopes in the world into existence, and had gotten the unparalleled grant for this one, could not be ignored. Sometimes Hale’s questions were ahead of anyone else’s on the project. Other times he was off on a tangent, and his questions wasted valuable time. He trusted the men he knew, members of his club, heads of institutions and corporations he had met personally, or who had been recommended to him by one of the old boys. Even if they pointed to the wrong man, to people who knew nothing about the telescope, and took up valuable time that was needed elsewhere, George Hale’s suggestions couldn’t be ignored.

When he returned from the extended trip to Europe, in the late spring of 1929 Hale checked into the sanatorium in Maine for more rest, woodcutting, and forced isolation. It was late spring before he finally went back to Pasadena and his solar laboratory. He joined the regular weekly meetings of the Observatory Committee, but his participation, like his occasional solar research on the spectrohelioscope at the laboratory, was increasingly frequently postponed or interrupted by his old bugaboos: the excruciating headaches, depression, and the demons. The reports from West Lynn, bringing more bad news about progress on the mirrors, aggravated the attacks. The project seemed rudderless.

In Pasadena, Francis Pease tried to refine his sketches into working plans. So many decisions depended on the mirror that it was
impossible to produce working drawings. Everyone pretended confidence—of course Thomson and Ellis would work out the problems in the fused-quartz technology and produce the mirror blank—but until they knew for sure that there would be a usable mirror, the basic engineering questions for a large telescope—How do you support a two-hundred-inch-diameter mirror so that it won’t change shape as the telescope moves? Where can observers get access to the light gathered by the great mirror? How do you point the machine with the precision that astronomers require and keep it tracking faint celestial objects as they move with the sidereal rotation of the heavens? How do you move a machine that large with no perceptible vibration?—were on hold.

The design questions were complicated by the fact that the designers still hadn’t agreed on the basic optics of the new telescope. Should it be a fast telescope, with a relatively large ratio between the diameter of the primary mirror and the distance of the primary focus from the mirror? For astronomers who were trying to photograph distant objects at the limits of detection of the telescope and photographic emulsions, the faster the telescope, the fainter the objects it would record with a short exposure. Those who had spent a whole night, or sometimes three whole nights, cramped and cold, with a bursting bladder, while they guided a telescope to keep the pinpoint of a faint star in the cross-hair of an eyepiece, knew the advantages of a fast telescope.

Spectroscopists usually favored longer focal lengths and used their devices at the Cassegrain or Coudé foci. But even for them a short focal length could have advantages by permitting a more compact telescope, which would ease the engineering requirements for the mountings and the dome to enclose the instrument and allow some flexibility in the siting of the alternate foci.

But the light-gathering power of a fast telescope comes at a price. Fast telescopes are more sensitive to light pollution. When Heber Curtis moved from the Lick Observatory to the Allegheny Observatory, in Pittsburgh, he discovered that he could only use slow, long-focal-length telescopes because of the light pollution. A fast telescope also requires a mirror of deep curvature, which is harder to grind and polish to shape. The deep curvature requires a thick mirror blank so that enough material will be left after the grinding to maintain the shape of the mirror. A thicker blank would also be more massive and take longer to adjust to changes in the ambient temperature in the observatory. For a mirror with a deposited surface, like the fused-quartz mirrors, a deep curvature would require either that the deposited layer be thick enough to accommodate the shape ground into the mirror, or that the molded quartz backing be ground into a rough spherical shape before they began spraying on the clear quartz layers. Either way it meant more complications for the already troubled work at GE.