Famous Givers and Their Gifts

by Sarah Knowles Bolton

Professor Burnham said in his Report, "The remarkable steadiness of the air, and the continued succession of nights of almost perfect definition, are conditions not to be hoped for in any place with which I am acquainted, and judging from the previous reports of the various observatories, are not to be met with elsewhere."

Meantime, even before Congress gave the land in 1876, Mr. D. O. Mills, one of the first trustees, had visited Professor Holden and Professor Newcomb at Washington to determine about the general plans for the Observatory. It was agreed that the latter should go to Europe to investigate the matter of procuring the glass necessary for a large reflector or refractor. It was finally decided that a refracting telescope was the best for the study of double stars and nebulæ, the moon's surface, etc., giving more distinctness and brilliancy, and being less subject to atmospheric disturbance.

Professor Newcomb experienced much difficulty in Europe in finding a firm ready to undertake to make a glass for a telescope larger and more powerful than any yet made. The firm of M. Feil & Sons, Paris, was finally chosen. Professor Newcomb wrote an interesting report of the process of making the glass.

"The materials," he said, "are mixed and melted in a clay pot holding from five hundred pounds to a ton, and are constantly stirred with an iron rod until the proper combination is obtained. The heat is then slowly diminished until the glass becomes too stiff to be stirred longer. Then the mass, pot and all, is placed in the annealing furnace. Here it must remain undisturbed for a period of a month or more, when it is taken out; the pot and the outside parts of the glass are broken away to find whether a lump suitable for the required disk can be found in the interior.

"If the interior were perfectly solid and homogeneous, there would be no further difficulty; the lump would be softened by heat, pressed into a flat disk, and reannealed, when the work would be complete. But in practice, the interior is always found to be crossed in every direction by veins of unequal density, which will injure the performance of the glass; and the great mechanical difficulty in the production of the disk is to cut these veins out and still leave a mass which can be pressed into a disk without any folding of the original surface."

The glass for a telescope is usually composed of a double convex lens of crown glass, and a plano-concave lens of flint glass. M. Feil & Sons made and shipped the latter, which weighed three hundred and seventy-five pounds, but broke the crown glass in packing it. Then during three years they made twenty unsuccessful trials before obtaining a perfect glass.

The cutting away of the clay pot and outside glass is a tedious process, requiring weeks and even months. No ordinary tools can be used. The pieces are "sawed by a wire working in sand and water.... When it is done," says Professor Newcomb, "the mass must be pressed into the shape of a disk, like a very thin grindstone, and in order to do this the lump must first be heated to the melting-point, so as to become plastic. But when Feil began to heat this large mass it flew to pieces." He took more and more time for heating, and finally succeeded.

The noted firm of Alvan Clark & Sons of Cambridge, Mass., did the polishing and shaping of the lenses, a labor requiring great skill and delicacy of workmanship. The objective glass was ordered in 1880, and reached Mount Hamilton late in 1886, having cost $51,000. It weighs with its cell 638 pounds. The Clarks would not undertake any larger objective than thirty-six inches. This was six inches larger than the great glass which they had made for the Imperial Observatory at Pulkowa, near St. Petersburg in Russia.

The glass, though an important part of the telescope, was only one of many things to be obtained. In 1876 Captain Richard S. Floyd, president of the Lick trustees, himself a graduate of the United States Naval Academy, met Professor Holden in London; and the latter became the planner and adviser, throughout the construction of the buildings and the telescope. Captain Floyd visited many observatories, and carried on a vast correspondence, amounting to several thousand letters, with astronomers and opticians all over the world.

Professor Holden was a graduate of West Point, had been a professor of mathematics in the navy, one of the astronomers at the Washington Observatory, in charge of several eclipse expeditions sent out by the government for observation, a member of various scientific societies in Europe as well as America, and associate member of the Royal Astronomical Society of England, and well-fitted for the position he was afterwards called to fill,—the directorship of the Lick Observatory. For some time he was also president of the University of California.