Figure 23. — Spectroscope made by Alvan Clark & Sons in 1877 for 

 use with the 9-inch refracting telescope at Princeton University. 

 As shown here, the spectrum is formed by a Rutherfurd diffraction 

 grating, but the instrument was also equipped with a glass prism 

 for this purpose. The spectroscope is now in the collections of the 

 Smithsonian Institution. The drawing is from Charles A. Young, 

 The Sun (New York, 1896), fig. 18, p. 69. 



Willets Point, New York Harbor. In 1880 they acquired an equatorial 

 refracting telescope made by Fauth & Co., with a 5^-inch objective lens 

 figured by the Clarks. 218a 



The U.S. Military Academy at West Point, New York, acquired a 

 Fitz equatorial refractor of 9% inches aperture in 1856; in 1875 the 

 Clarks reworked the objective of this instrument at a cost of $500. 219 In 

 1883 the West Shore Railroad, which had run a tunnel directly under 

 the old observatory, built a new observatory for the cadets. The following 



2I?a J. H. Willard, Practical Astronomy at the Engineer School of Application at Willets 

 Point, N. T. H., 1 881 (Willets Point, 1882). 



219 Alvan Clark to Peter S. Michie, 1 September 1875 (letter in U.S. Military 

 Academy Library). 



96 



