THE GREAT YERKES LENS FINISHED.
THE lens for the great telescope given by Mr. Yerkes, the Chicago millionaire, to the University of that city, is now ready, according to the Scientific American. The observatory that is to hold it will be far away from the murky air of Chicago, on the border of a Wisconsin lake. Says the authority just named: "The lens of the great telescope of the new observatory at Lake Geneva, Wis., the finest and largest telescope lens in the world, has been completed after two and a half years' labor, and now lies at the workshop of Prof. Alvan Clark, in Cambridge, awaiting the orders of the Chicago University authorities. Its focal distance is 61 feet, the extreme diameter of the clear aperture is 41 3/8 inches. The crown is about 3 inches thick at the middle and 1 1/4 inches thick at the outer edges, and weighs 205 pounds. The flint weighs 310 pounds. The lens and its iron ring and cell weigh about 1,000 pounds. The cost of the glass plates in Paris was $40,000, and the entire cost of the lens is estimated to have been $100,000. For its journey west it will be wrapped in flannel and bedded in curled hair in a box mounted on springs and packed with excelsior in a larger box. It will ride in the center of a parlor car, and will be accompanied by four men."—Literary Digest.