Figure 28. — Alvan Graham Clark and Carl A. R. Lundin with the 

 crown glass component of the 40-inch aperture objective lens for 

 the Yerkes Observatory. From George E. Hale, Study of Stellar 

 Evolution (Chicago, 1908), plate xlv. 



clock and spring governor of the Yale telescope. 264 Later Clark additions 

 to the observatory included a portable refractor of 4% inches aperture, a 

 conical pendulum chronograph, a multiple ring micrometer, and a 

 spectroscope of seven prisms twice traversed. 265 



The Winchester Observatory at Yale tried unsuccessfully to obtain 

 a Clark instrument. Their Repsold heliometer, the first such instrument 

 in the United States, arrived in time for use during the 1882 Transit of 

 Venus. The optical work had been done by Merz only after Alvan Clark 

 had declined the responsibility of dividing the 6-inch objective. 266 The 



264 J. E. Nourse, "Observatories in the United States," Harpers New Monthly 

 Magazine, vol. 49 (1874), p. 530. 



265 Edward S. Holden, "Astronomy," Annual Record of Science and Industry (1878) , 

 pp. 68-69. 



266 A. M. Clerke, "The Yale College Measurement of the Pleiades," Sidereal 

 Messenger, vol. 6 (1887), p. 254. 



1 1 1 



