The Lick Telescope

International Tract and Missionary Society · Oakland, California · May 13, 1886

FromSigns of the Times, Vol. 12, No. 18.

The Lick Telescope.

In the basement of an unpretentious brick building on Henry Street, Cambridgesport, is probably the most costly table in the country. Its top is a circular disk of glass just a yard in diameter, and of the kind commercially known as crown glass. To the ordinary observer it presents the appearance of only a circle of plain glass, such as might be cut from hundreds of shop windows in this city, with the edges ground down. But this transparent table covering is worth $25,000, and its mate of flint glass in an adjoining room is worth $25,000 more. If by any accident these two pieces of glass should be destroyed, $25,000,000 could not duplicate them within the next six months. Together they are to form the lens of the great Lick telescope, which when finished will be the largest refracting telescope in the world.

In the manufacture of this instrument for the Lick Observatory the makers have no rivals to excel, the telescope they have but recently completed for the Russian Government already being the largest finished instrument in the world. This has a lens thirty inches in diameter, six inches less than the one on which they are now employed. Before this there were two twenty-seven-inch in Europe, one of which is in Vienna, once the largest known. The two largest in this country are twenty-six-inch—one at the Naval Observatory, Washington, and the other in the McCormick Observatory, connected with the University of Virginia at Charlottesville, both of which were made by the Messrs. Clark.

The discs for the Lick telescope were cast at an establishment in Paris, the only place in the world, with the exception of Birmingham, England, where work of this magnitude is attempted. The order for the casting was given five years ago, but so numerous were the failures that it was not until last September that the blocks were received here. Since that time Mr. Clark and his sons have been constantly engaged in the task of cutting them down to the proper curvature, and they do not expect to complete the work much before the latter part of next fall, and indeed are not ready to say positively that it will be done then.

Some idea of the amount of careful labor involved may be gained from the statement made by one of these gentlemen, that although the glasses came here partially ground down and polished, they have already taken from both over 100 pounds in weight of material. At first a rough grinding was done by machinery, but for months past only the hand has been used, and they have now reached that stage where the removal of a few grains more or less from the wrong place would ruin them. It is only by constantly testing with the trained eye and careful manipulation with the skilled hand of the operator that the work is now carried slowly on. The only instrument used is the hand smeared with rouge—a polishing substance finer than the finest emery.

Possibly some of our readers may ask why two qualities of glass are necessary for one lens, but probably a large portion of them are aware that double, or what are known as achromatic, lenses are necessary even in the cheapest of photographic instruments. In these and the smaller telescopes the two glasses are cemented together, generally with Canada balsam, but in this new instrument, and indeed in others made at Messrs. Clark's establishment, the two halves of the lens are set six inches apart in their iron frame. This having convenient

openings on its outer rim allows of the glasses being properly cleaned on each side, and does away with some disadvantages resulting from atmospheric changes. The two glasses with their metal frame weigh something over 700 pounds.

When mounted in its lofty dome this telescope will be one of the wonders of the world, and, doubtless, for the next few years it will be the Mecca toward which devout astronomers of all countries will make pilgrimages. Some idea of the power of this instrument may be gained from the statement recently made by an astronomer, that, gazing at the moon through this mighty annihilator of space, the orb of night, really about 240,000 miles away, would be brought to within less than a hundred miles of the eye of the beholder.

Mount Hamilton, where the telescope is to be placed, is in Santa Clara County, California. The mountain has three peaks, the eastern one being 4,440 feet high, the middle peak 4,350, and the third or Observatory Peak originally 4,276. Mr. Lick devoted $700,000 to the construction of the buildings and for a "telescope superior to and more powerful than any telescope yet made," with the proviso that Santa Clara County should construct a carriage road to the top of the mountain. This was accomplished in 1876 at a cost of $78,000, and is a marvel of engineering skill. The buildings and instruments now completed and in position are the observers' house, the transit house, the photo-heliograph and photograph house, the north dome and the twelve-inch equatorial refractor, the meridian circle house and the six-and-one-half-inch meridian circle, many auxiliary instruments, such as chronometer, sidereal clocks, etc., and a number of portable telescopes. The dome which is to cover the great telescope will probably be constructed of steel plates, will be about seventy-five feet in diameter, and will weigh about ninety-three tons.—Boston Transcript.