Figure 12.—Hodge’s method of cutting the checker grooves. (From Preston, fig. 6.)
The Hodge company made several (probably three) grinding tools for Peate. One was about 12 inches in diameter, and was to be used by hand. Two of the larger tools were provided with the male member of a ball and socket joint and were to be power driven. They were 30 and 48 inches in diameter, respectively. The largest was grooved to a waffle-like surface on its convex face. These grooves were about ½ inch wide and 3/16 inch deep. This pattern was ground by placing the tool face up on a wheeled buggy, which rode on cambered oak rails. As it was pushed along the length of the rail the grinding wheel on the radius arm cut one groove. When the groove had been cut, the radius arm was moved 2 inches along a line shaft and another groove cut. When all the grooves had been cut in one direction the tool was turned 90 degrees on the buggy and the other set of grooves was ground. The grinding of this tool took many weeks, and making the tools and apparatus for Peate may have kept Hodge busy for nearly six months.[29]
Figure 13.—Face of largest grinding tool made by Hodge for Peate. (From Preston, fig. 5b.)
The history of Peate’s 62-inch mirror probably would have remained as obscure as that of his others except for the furor which arose over casting the disc. The Erie Conference made no attempt to publicize this project, and both Hodge Manufacturing and Standard Plate Glass accepted Dr. Peate’s contracts as somewhat unusual but hardly newsworthy jobs. But when the glass trade became aware of Standard’s intention to cast this disc, a mighty outcry arose. Instead of encouraging Standard to complete this novel task the National Glass Budget, one of the leading trade journals, reviled them as “bumpkins” for attempting something that even the great glassmakers of Europe would not do.
It is hard to imagine why the trade journal so strenuously objected to Standard’s attempt. It has been suggested that it derived from the fact that Standard Plate Glass just previous to that time had refused to join in a combination of Pittsburgh companies which had set up a glass trust.[30] Or it is possible that the young industry was afraid that an overly ambitious project doomed to failure might open American glassmaking to European ridicule and so harm the entire American industry. Whatever the reason, the Budget ridiculed Standard Plate Glass, and later Dr. Peate, for the attempt. They argued that it could not be done, but that if it were possible Pittsburgh would be the logical place to try it. Criticism and unfavorable comment came from other sources also, including “university professors from Meadville” (evidently Allegheny College).[31] Nonetheless, Standard Plate Glass started the project.
George Howard was in charge of the casting operation. He planned to use the glass from a pot regularly used in the routine manufacture of plate glass. However, certain modifications were introduced in the procedure. The glass was to be poured on the traveling casting table, upon which was placed a circular mold made up of two semicircles of a special charcoal iron obtained from Philadelphia. This iron was not apt to generate bubbles of gas when in contact with the molten glass.
The iron mold was hinged at one joint of the semicircles, and the other joint was bolted. After the cast was poured it would be allowed to cool somewhat. When it was judged cool enough, it would be pushed into a kiln to be annealed. After it had remained in the kiln a certain length of time—again based simply on judgement—a quantity of pre-heated sand was to be poured over the mold as insulation. A further innovation was the use of a zinc sheet placed on the underside of the mold to avoid the possibility of trouble from grease on the casting table. This was the initial plan of operation.
Sometime early in 1895 the first attempt was made. It was an immediate failure. The zinc sheet, intended to protect the cast from grease, volatilized when the molten glass was poured on it, bubbled up through the glass, and, of course, ruined the cast.