The Perfect Machine (32 page)

Ellis carried his campaign around Hale, going out to Little Compton, Rhode Island, where Max Mason was on vacation for Labor Day. He told Mason that Hale’s demands were impossible. What would your best price for each disk be? Mason asked. Ellis said GE simply couldn’t commit to a firm price. The next day, Hale and Mason met Ellis at the University Club in New York. Together the three went out to Gerard Swope’s country house near Ossining. Swope had prepared for the meeting by discussing the matter with C. E. Eveleth, chief engineer of GE’s Schenectady works. Swope’s best estimate was that the cost of a quartz disk would be an additional $1 million, perhaps more. Given the experimental nature of the work, GE could not guarantee that it would be able to produce the disks at that price. Walter Adams later estimated that if they extrapolated the rate of expenditure at GE during the spring and summer of 1931, the total cost for the mirrors would be closer to $2.5 million, almost half the budget for the telescope. Everyone at the meeting knew it was a formal closure: a final polite lunch before the inevitable divorce.

Hale continued his round of courtesy calls by going up to West Lynn to talk personally with Elihu Thomson. The two men had known one another for more than a quarter century. They were titans in their fields, Thomson the inventor who could produce solutions for any problem, Hale the grand old man of solar physics and the builder of machines to see to the edge of the universe. For years, at the annual meetings of the AAS or the National Academy of Sciences, they had talked of pooling their skills, and most outside observers would have bet on the success of a collaboration. Neither man was accustomed to failure. Thomson had a reputation for doing what the scientists said couldn’t be done. He had taken on much tougher challenges than this one, and had succeeded. If only Caltech would commit the funds, he no doubt told Hale, GE would produce the mirrors.

For the record, they later exchanged stiffly formal letters, congratulating and thanking each other for the contributions to science and technology that the experiments with fused quartz had provided.

Five days after he met with Swope, Hale held a meeting at the University Club in New York with Mason and three representatives from the Corning Corporation: O. A. Gage, the head of the Optical Glass Division; J. C. Hostetter, the director for special projects in the division; and George McCauley, the chief scientist. McCauley summarized Corning’s experiments on telescope mirror disks. The variety of Pyrex that seemed the most promising had a coefficient of expansion three times that of quartz but one-third that of plate glass. The only potential problem McCauley foresaw was in annealing the glass—not that it couldn’t be done, but that no one had ever tried to anneal large masses of glass.
Hale was impressed with the no-nonsense technical confidence of the Corning people, especially McCauley.

A week later, on October 14, the group met again, this time joined by Dr. Day and by General Carty of AT&T, still one of Hale’s most trusted advisers. The Corning group was ready with samples of Pyrex glass, showing the kinds of surface that would emerge if different powdered materials were used to coat the refractory bricks of a mold before the glass was poured. Corning also presented a budget and a timetable—exactly what GE had never been able to deliver. Hostetter, McCauley’s boss in the research division at Corning, laid out the budget. The minimum cost for three 60-inch disks, one 60-by-80-inch oval disk, a 120-inch disk, and the two-hundred-inch disk was $150,000. Unanticipated difficulties or repeated castings could push the figure as high as $300,000. The use of surplus equipment from the GE effort in West Lynn, or a disk design that would require less glass, such as a hole in the center or ribbed backs, would reduce the cost. He estimated that Corning could finish the mirrors in a little more than a year and a half from the time they got the go-ahead. If a second run were necessary for each mirror, the time might stretch to as long as thirty-one months.

The division of responsibility was as clear as the budget: Corning would expect Hale and his group to work out the optimum design for the disks, taking into account “best glass practice.” Corning would take care of annealing and would investigate shipping possibilities.

The cool decisiveness of the Corning people impressed Hale and his colleagues. And McCauley liked Hale’s idea that the each disk should be a model for the next. As a start he proposed that Corning would mold a 26-inch solid disk, then a 30-inch disk with a ribbed back like the designs that had been discussed at Caltech but never tried on a mirror. Once the 30-inch disk was ground and polished into a mirror, Corning would proceed to a series of Pyrex disks, a 60-inch, a 120-inch, and the two-hundred-inch—each based on the experiences with the previous ones. If the two-hundred-inch could be successfully cast, there would be further orders for additional 60-inch mirrors and other special-purpose mirrors. Hale agreed that if the project were to go ahead, the final price to the Observatory Council would be computed on a “cost plus” basis. The “plus” was a 10 percent profit that Corning would bill only after the disks were figured into mirrors and accepted by the Observatory Council.

Hale raised one other topic at the meeting. If the Observatory Council were to go ahead with an order for Pyrex disks, he said, they wanted no publicity of any kind. The failure of the quartz project was an embarrassment. More than $600,000, one-tenth of the entire telescope budget, had been expended on experiments that had not produced a single satisfactory mirror. At a time when eight million Americans were unemployed and the median income for an American family was $1,231 per year, $600,000 was a big expenditure to justify. Hale, with the reticence of a scientist, had resented the stream of press releases from GE. The
research necessary to build the telescope, like the observations of an astronomer, were raw data, scientific work in progress, not fodder for the publicity mill.

GE’s publicity had ultimately backfired. A few newspapers picked up on their final releases about the sixty-inch disk, and asked in editorials whether big businesses weren’t “exhausting [themselves] in attempting to outbid one another for the privilege of building the ‘world’s greatest telescope’ at a fabulous price.” Three years before, GE had been proud to count itself among the builders of the telescope. Now the publicity department scurried to dissociate itself from the project.

McCauley went to work the day after the meeting in New York.

Trained as a physicist, he shared Hale’s attitude about publicity. Although he had never been involved with a highly publicized project, McCauley had read enough journalists’ reports to know that when reporters were eager for news, they often “insisted on forgetting the plain scientific facts and achievements given them while publishing a dramatical romance of their own invention which whatever scientific facts used garbled as to render them unscientific.”

Fortunately Corning was a quiet company, secluded amid the rolling hills and narrow winding valleys of the southern tier of New York State, well off the beaten paths to the vacation areas around the Finger Lakes or Niagara Falls. Few tourists came to Corning in the early 1930s, and the town was content to go its quiet way. The company had been known for its research—Corning had supplied the glass envelope for Edison’s incandescent filament to create the electric lamp, and Corning research had produced the Pyrex brand of heat-resisting glass—but the company had never been overeager to publicize itself. The Corning memorandums summarizing the meeting didn’t even mention the publicity issue. An internal memorandum was quietly circulated to request that all reporting on the new project be oral only, with no written statements that might get out to snooping reporters.

McCauley had successfully cast a disk in his first try, years before, but he was a cautious man. He recruited Ralph Newman, a mold maker from the Corning Laboratory, and Wallace Woods, an experienced glass worker from the blowing room, for a series of experiments to explore the problems of molding of a large telescope mirror.

Compared to the ferociously complex process of spraying fused quartz, molding glass seems simple. A melting tank of refractory brick is filled with sand, soda, lime, and borax and heated with gas jets suspended from an arched roof until the mix melts into glass. Depending on the intended use, the mixture is fined—maintained at working temperature—for a period of days or even weeks to allow the bubbles that form within the mixture to rise to the surface. The glass in the tank is then ready to be molded or blown into shape. The process is straightforward
and tried; for forms of glass used in undemanding applications, glassmaking hasn’t changed much in thousands of years.

For optical glass, which would be sensitive to contaminants in the raw materials, from the bricks and cements used to build the tank, and from tools used to stir or transfer the glass, the process is a little more complicated. In glass for a critical application, like a telescope mirror, contaminants can weaken the internal structure of the glass or introduce strains that would ultimately distort the disk.

Even with ordinary plate glass, maintaining the purity and consistency of a large mass of molten glass while transferring it from a tank to a mold is a challenge. Borosilicate glasses, like Pyrex, are even more demanding, because at the extremely high temperatures required to melt borosilicates, tank and tool materials can give off gaseous contaminants or even begin to melt into the glass mixture.

Typically, a large production tank in the glass factory might produce twenty tons of glass over a twenty-four-hour period. The glass is dribbled out, depending on the articles produced, at anywhere from a few pounds at a time to a continuous stream of thirty to forty pounds per minute. At that rate of use the ingredients for new glass can be melted at one end of the tank as fast as the ready glass is removed from the working end at the other.

A large telescope disk would require twenty tons of glass all at once. No one had ever fabricated a piece of glass that large or come up with a procedure to relieve the stresses in the glass so it could be used for a high-precision instrument. The requirements for ribs in the backs of the disks, to reduce the thickness of the glass and the weight of the disk without compromising its rigidity, meant that McCauley needed a method of molding glass with complex structures. Corning had vast experience in molding and blowing complex shapes into small units of glass. But no one had experience with molds built to withstand the heat of borosilicate glasses for as long as it would take to fill a mold with twenty tons of Pyrex.

McCauley began with some basic assumptions: Given the schedule and budget of the project, they would not conduct costly experiments to develop new glasses and methods of melting or working glass. They would not build large machines for tasks that could be performed by manpower at lower cost. A surplus melting tank, idled by lack of demand, would be used to melt the glass, rather than a custom facility.

For the first experiments McCauley had Ralph Newman build test molds to a standard pattern, with two refractory bricks for the bottom, five bricks for the sides, and wire and angle irons to hold up the corners of the mold. Wally Woods, the experienced glass man, would then pour molten 702 Pyrex, the same formula that had worked in the earlier pours, from a test tank into each mold so they could study the interactions of glass and brick.

Newman started with the same refractory bricks that had worked
successfully for a test disk years before, selecting good bricks, without cracks, for his molds. Each time Wally Woods poured hot glass into one of the new molds, a cloud of bubbles would erupt in the glass. Nothing obvious was wrong. McCauley dug up the records on the bricks and discovered that the leftovers from the shipment that had worked for molds in 1929 had been stored in a damp room under one of the glass factories. The bricks had wicked up moisture, which turned to steam when the molten glass was poured into the mold.

He had Newman switch to a new grade of brick. That cured the bubbles: Even when the new Armstrong C-25 bricks were soaked in water before the glass was poured, there were no steam bubbles in the molded glass. But success begat new problems: After a few hours in contact with the molten glass the surface of the brick emitted gas bubbles that left a rough surface on the glass. McCauley’s solution was to brush the mold surfaces with a paste of silica flour and water before the glass was poured.

A satisfactory mold material was only the first step. At the meetings in New York, Hale had described the problems with the one-hundred-inch plate-glass disk on the Hooker telescope, especially the bubbles that marked the layers of glass from each of the three pours. Corning’s production lines for Pyrex consumer and laboratory goods worked by filling molds directly from a big melting tank. The technique wouldn’t work for a telescope mirror, because the mirrors had to be made of exceptionally pure glass, and the purest glass in any tank comes from the center of the batch, which is not in contact with the walls of the melting tank.

McCauley’s solution was to try an old technology. Ladling, which had been abandoned for production glass work almost everywhere, had advantages for the work on disks. Ladles can take the glass from the center of the tank. They allow the glass to be inspected before it is poured, and because the glass begins to cure against the walls of the ladle, leaving a ladle heel that is later broken out, the glass that remains viscous enough to pour into the mold—generally between half and two-thirds of the contents of the ladle—has effectively only been in contact with glass, not with materials that could introduce contaminations. By introducing the glass into the mold in ladle-size installments, the mold does not face the sudden heat shock of a huge mass of hot molten glass. The alternative to ladles, arrangement of spouts to pour glass from pots into the mold, would have required experimental heated spouts, a turntable for the mold to provide even filling, and a procedure to cut off the spout from the mold and heal the scar. McCauley’s instinct was exactly opposite to those of Ellis and Thomson and GE: He wanted the simplest, cheapest, and safest process.