The Perfect Machine (50 page)

Intuitively Kroon guessed that Hodgkinson’s figure was too high. Kroon had a strong background in physics and applied mechanics. The engineering formulas were fresh in his head. He studied Russell Porter’s sketches of a possible bearing and realized that Hodgkinson had calculated the power required as if the entire oil flow were through an orifice. In fact the oil would be spread in a film between the two bearing surfaces. When Kroon recalculated the oil pressure as a film flow, the needed horsepower dropped by a factor of one thousand. With his new calculations, the pumps for oil bearings would need less than one horsepower.

Kroon showed his figures to other engineers and scientists in the basement of the astrophysics building. He was greeted with skepticism. He offered to demonstrate that his oil bearings would work, and the Engineering Committee approved the expenditure of fifty-eight dollars for an oil pump to test the idea.

At Westinghouse a test model would require detailed working drawings, approvals of the plans, requisitions for materials and model-makers’ time, layers of authorizations, and an interval to schedule the project in the model making shops. Caltech, even with Sandy McDowell’s efforts to introduce proper procedures, didn’t run that way. The astrophysics machine shop was in the building next door. There were seventy machinists, under the direction of Sherburne, who had been recruited to run the shop from his own machine shop in Pasadena. Sherburne, a first-rate machinist himself, seemed to know the best machine operators and machinists. His shop turned out parts for the Schmidt telescope, new instruments for testing on the Mount Wilson telescopes, and models for the engineers and telescope designers with a minimum of paperwork and bureaucratic hassling.

When Kroon went over to the machine shop late in the afternoon with his sketches, he was introduced to a machinist and told to explain what he wanted.

“When do you need it?” the machinist asked.

“As soon as possible,” Kroon answered. Looking at the huge shop, filled with machines and work in various stages of completion, he assumed that it would be weeks, maybe even months, before he had his model.

Early the next the morning, the machinist came over with the model Kroon had asked for. After the formality of work at the Federal Institute in Switzerland and the bureaucracy at Westinghouse, Kroon was amazed. The machinist had worked most of the night to finish the model.

Later that morning Kroon invited the engineers and scientists in the astrophysics building to watch a demonstration. The test model was a three-foot-square steel slab, six inches thick, loaded with lead weights to a total weight of 12,000 pounds, on an inclined plane. Three oil ports in the inclined plane were hooked to a pump and reservoir of oil. The slab was suspended on the equivalent of a hinge on one side so it could be moved over the pads, but the friction of the weight was so great that if the slab was moved from one side of the plane to the other, it remained in place.

Then Kroon started the pump. Oil pumped through the three orifices and spread into a thin film under the weight. When the pump reached full pressure, Kroon nudged the heavy weight to one side. It swung over, then back and forth. By measuring the amplitude of the swings of the pendulum, Kroon could measure the effectiveness of the oil film as a bearing surface. At the optimum setting, the weight oscillated freely from one side to the other, almost frictionless.

Even Pease, who had been the most skeptical about oil bearings, came around after Kroon’s demonstration. The clearance between the weight and the inclined plane was only a few thousandths of an inch, but it behaved as Kroon’s calculations predicted: A film of oil a few molecules thick could support hundreds of thousands of pounds of telescope. The coefficient of friction was so low that a fractional horsepower motor would easily move the telescope. Kroon’s experiment was expanded to a large weighted bearing, carrying the estimated five-hundred-ton load of the telescope. Moving it at the normal driving speed required fifty foot-pounds; Kroon calculated that a ball bearing would require thirty thousand foot-pounds of driving force to move the same load.

Kroon’s final design for the horseshoe bearing used four cavities in each pad for the oil orifices. Limiting the flow through the orifices from 600 to 300 psi (pounds per square inch) provided additional stability. In less than a week, Kroon finished his calculations; his sketches and figures, some on the back of an envelope, went to a draftsman. The bearing problem, which had haunted the telescope since Pease’s earliest designs fifteen years before, was solved.

Next Kroon tackled the design of the horseshoe. If the telescope was to move smoothly, the bearing surface had to be stiff enough to remain round as the horseshoe tipped from resting on one edge, around through the bottom of the
and over to the other side.

The earliest ideas for the horseshoe were for an open truss work design that would be riveted together in the field, the construction that
had been used for the one-hundred-inch telescope. To remain rigid with riveted construction, the horseshoe would have required such heavy plates, and such closely spaced stiffening diaphragms, that the whole horseshoe design was almost abandoned. The strength of a welded construction from solid plates made the horseshoe possible again. The examples of the penstocks and cylinder gates of the huge Boulder Dam showed that massive structures could be welded. Still, the design was tricky. The loads on the horseshoe would put a combination of compression and shear loads on large plates of steel. The completed horseshoe would be some forty-six feet across, far too large to ship as a single unit, so the design also had to permit fabrication in sections small enough to move by rail, ship, and ultimately truck to the mountaintop. The challenge was to design internal stiffening members that would retain the needed stiffness under load and still be arranged in a way that would allow the internal structure of the horseshoe to be welded.

Kroon knew that it was possible, with enough calculation, to arrive at an analytic solution to the design. But he also remembered from his days as a machinist apprentice how often an analytic design by an engineer had made no provision for the difficulties of manufacture. One afternoon at the cottage on Los Robles, while his three-month-old son played on the floor, Kroon cut out sections of cardboard and glued them together in different configurations. He tested each model with tiny weights, measuring the deflection of the cardboard panels with a ruler. By the end of the afternoon, he had an internal design that met all his requirements. When he calculated the stresses the next week, they worked.

Kroon found the style of work in California, where an engineer could take rough drawings to the machine shop without review, authorization, or certification, both refreshing and productive. Westinghouse had sent him to California for six months. In the first two months he had solved two of the thorniest design problems. Even Pease was delighted to see more of the design details directed toward Kroon.

Serrurier’s tube design, with his diagonal trusses, had solved the problem of building a relatively lightweight yet rigid tube for the telescope. Kroon was handed the problem of how to pivot the tube on bearings. Ball bearings could carry the load of the tube—only a fraction of the load on the horseshoe bearings. But any play in the mounting or strains passed to the bearings would distort the tube, and the careful alignment of the optical system. Theodor von Karmann, from the Aeronautics Department, had been studying the problem of the declination trunions, and had his men calculating the stresses.

Kroon had never seen a big telescope. He had no idea how tubes were usually pivoted in a telescope. But as soon as he saw the problem, he had an idea. The spokes of a bicycle wheel are stiff in tension
and compression, though flexible in bending. A light bicycle wheel remains round even with a heavy rider going over a big bump. A ring of spokes, running from the telescope tube to the bearings, he reasoned, would locate the tube firmly. This problem was too tough to model in cardboard, so he calculated the loads and drew up sketches for the draftsmen. Once again his solution looked too simple. Von Karmann, the famed Caltech professor, looked at the thin spokes and asked, “Did you calculate the buckling loads?”

Kroon, awed that a world-famous professor was reviewing his sketch, hesitantly pointed out that the tension on the opposite spoke would balance the compression, maintaining the system in alignment. Von Karmann agreed, and yet another solution from the gentle Dutchman found its way into the telescope.

Kroon’s gentle manner served him well. Though an outsider among a crew of Caltech astronomers and engineers, he was accepted as one of the team, invited on the camping trips in the desert led by Russell Porter, where the nighttime naked-eye star observations were interrupted by coyote howls. Kroon was in Pasadena when the mirror arrived, and like the others he felt the sudden glare of the publicity spotlights on the project he hadn’t even heard of a year before.

His last project was the south bearing of the telescope, which would share the load of the entire fork with the great horseshoe bearing. He spent the Easter weekend “monkeying around at home” in the little Los Robles cottage, trying to think of a design that would create no forces to disturb structure. When he got stuck in his monkeying, he would practice music or play with his infant son. Finally, what emerged was a ball on oil bearing pads. The ball design would work under the enormous thrust loads of the south bearing, and could be powered by the same pump system that served the pads for the great horseshoe.

With the six months up and the design problems solved, Rein Kroon packed up and moved back to Philadelphia. Like the hero of a Western, he had come to town, cleaned up the troubles, saddled up, and ridden on, to other towns and other problems. He never saw the telescope.

23
The Endless Task

John Anderson had trouble sleeping the night the disk arrived at Caltech.

The glass disk had been unloaded from the Belyea Brothers truck onto a heavy timber easel strong enough to support three times the weight of the disk. On Easter Sunday, Marcus Brown and his workmen removed the front and back of the steel packing crate, revealing the marred face of the disk and the beautiful honeycomb structure of the back. Like the Corning officials when they had exhibited the disk to the public, “Brownie” put the disk on the easel with the back showing, although in his case it was only because the initial work was scheduled for the back of the disk. Brownie fretted for a long time to make sure the disk was secure. The circular sections of the crate were still in place around the edge of the disk, and the overhead crane that ran the length of the optics shop was left attached to the slings that fastened to two points on the crate. Anderson came over to check the easel and supports for the disk when it was finally secured in the optics lab.

In the middle of the night Anderson began to wonder what would happen if an earthquake hit Pasadena. From his work on seismographs, he knew how frequent earthquakes were in Southern California. What if an earthquake jostled the easel while the disk was still hooked up to the overhead crane? The thought was enough to get him to bolt from bed and drive to the optics lab. There was no earthquake that night. The disk was where they had put it. It was only the first of many nights that John Anderson lay awake worrying about the great mirror.

In 1935 and 1936 there were plenty of applicants for work in the optics lab. The pay wasn’t great: starters got forty cents an hour; the most experienced men ninety-five cents an hour. But when word got out about a steady job, working indoors, men lined up. Some had no work; others wanted better work. Mel Johnson, a young mechanic,
was willing to give up a one-hundred-dollar-a-month salary for the promise of steady work. Brownie warned each applicant with the same speech: “Glass won’t ever do what you expect. It’s human. It has as many moods as a movie star, and no two of ’em are alike. You’ve got to know them all. And remember this: If you don’t know what you’re doing, don’t do anything till you find out.”

The men listened, nodded, and went to work on a trial project. Most left after a few days or a week. It took special talents to work on optics, to stand up to the routine. Previous career was no indication of who had the temperament. The men Brownie hired included a failed insurance salesman, a man who had worked on a garbage truck, and a pump jockey from a filling station.

Work began every day at 8:00 A.M. Everyone who worked in the optics lab changed into a white shirt and trousers, cotton hospital uniforms, and canvas sneakers. Sometimes, depending on the work, the men needed a clean uniform each day. At lunch they changed out of the uniforms, ate from brown bags, and played handball outside and then changed back into the uniforms for four more hours of the routine. There were no breaks. Brownie rolled Bull Durham cigarettes and sometimes chewed Bull Durham while he worked, and others picked up the habit. A few men were interested in optics, and Anderson agreed to give evening classes to explain the mysteries of the mirrors and lenses. Otherwise the only times the lab was quiet enough for conversation was during lunch or while the men showered and dressed. The favorite topic was guns and hunting. Anderson was a hunter and had once shot a polar bear. But the gap between Caltech professors and Mount Wilson astronomers—the men who wore suits and ties—and the workers who actually ground the glass, was too great for small talk. Russell Porter, at heart still an amateur telescope maker, sometimes worked on his own projects in the optics lab. He was too deaf for much conversation.