THE PROGRESS OF SCIENCE 



411 



The Thaw Photographic Refractor. 



mechanical flight, now recognized as 

 having formed the basis for present- 

 day success in this field. 



After Langley had been called to 

 the secretaryship of the Smithsonian 

 Institution at Washington, he was suc- 

 ceeded at Allegheny by his former 

 assistant, James Edward Keeler. His 

 short directorship was marked by the 

 brilliant proof of the meteoric com- 

 position of Saturn 's rings, one of the 

 best planned and most striking ob- 

 servations of modern astronomy. 

 Keeler persistently urged the necessity 

 of removing the observatory from its 

 original site, upon which the rapidly 

 growing city had by this time seriously 

 encroached. Steps to bring about this 

 removal were under way, but they 

 were temporarily halted in 1S98, when 

 Keeler was called to the directorship 

 of the Lick Observatory. But shortly 



afterwards these efforts weie vigorously 

 renewed by Dr. John A. Brashear, who 

 lias been chairman of the observatory 

 committee since 1894. The new ob- 

 servatory as it stands to-day is in 

 large measure a tribute to the respect 

 and affection in which Dr. Brashear is 

 held by the people of Pittsburgh. 



The plans for the new observatory 

 and its equipment are due to Keeler 's 

 immediate successor, Professor F. L. 

 O. Wadsworth. and to the present di- 

 rector, Dr. Frank Schlesinger. The 

 principal instruments are the old 13- 

 inch refracting telescope, a 30-inch 

 reflecting telescope (a memorial to 

 Keeler), and a 30-inch refracting tele- 

 scope (a memorial to William Thaw 

 and his son. William Thaw, Jr.). The 

 last of these telescopes is not quite 

 complete, as the objective remains to 

 be supplied. 



