\\'hen the work of equipping the Blount Wilson Observatory 

 was in progress Mr. Hooker asked, "Why not have a hundred- 

 inch telescope on the mountain? It would be the largest in the 

 world for many years, and might accomplish great things for 

 astronomical science." The reply was made that the cost of a 

 glass of that size and its mounting would be so great that such a 

 project would be impracticable. "How much would such a lens 

 cost?" asked Mr. Hooker. "Probably not less than $50,000," was 

 the ofif-hand reply. "Put me down for that $50,000," was Mr. 

 Hookers impulsive exclamation, and the magic glass was or- 

 dered at once from the French Plate Glass Co. in Europe. 



Several unsuccesful attempts were made to produce a disc 

 large enough to fill the order. But at last one was made by three 

 pourings of the melted material. It formed a circular mass 101 

 inches in diameter and 13 inches in thickness. The three pour- 

 ings did not mix so as to form an absolutely homogeneous mass, 

 but it was sent to its destination in Pasadena for trial, to be 

 accepted and paid for if it proved satisfactory. 



The Director of the Mount Wilson Solar Observatory, Dr. 

 George E. Hale, a man of scientific and mechanical acumen, 

 deemed the experiment worth while, and the grinding, polishing 

 and silvering of the great mirror has been accomplished under 

 the special direction of Professor G. W^ Ritchey, whose previous 

 experience in optical work ensured the best results. 



But, to carry forward this great enterprise, give the giant 

 mirror an adequate mounting, make all its possibilities available 

 for practical use, large additional sums were required, and these 

 were forthcoming from the munificent fund of the Carnegie 

 Institution, founded by that great philanthropist, Andrew Car- 

 negie. 



The immense castings for the equatorial mounting of the 

 telescope, weighing about one hundred tons, had been ordered 

 from the large works at Fore River in the East. These are 

 alread}^ in position in the magnificent observatory building con- 

 structed expressly to house the future telescope. The building 

 and the dome which surmounts it are 100 feet in diameter — 

 far the laregst ever constructed to house a single telescope. The 

 great dome and the revolving observing platform, as well as the 

 massive mounting, are all moved by electric power, and the 

 touch of an electric button sets them in motion. A ten-ton electric 

 crane is used in placing the various sections of machinery. 



When the crate containing the 100-inch mirror was backed 

 into the wide entrance of the observatory to a place beneath the 

 hole in the several floorings above, it was unfastened from the 

 truck and siezed by the crane and lifted to the observing floor 

 forty feet above. Here it will be taken from the box and fitted 



55 



