In 1869 or 1870 Justus M. Silliman, then a student pursuing the 

 chemical course at the Rensselaer Polytechnic Institute, examined the 

 flame of the Bessemer process with a spectroscope made by Alvan Clark. 

 This instrument, a common laboratory type, had a collimator, a viewing 

 telescope, and a third tube carrying a graduated scale; the spectrum 

 was formed by an equiangular flint glass prism. 207a 



Just as Charles A. Young had been advisor to Mount Holyoke College 

 (q.v. ), so David Todd of Amherst supervised the construction and out- 

 fitting of an astronomical observatory for the women of Smith College 

 in Northampton, Massachusetts. Among the instruments he chose, and 

 which were installed in 1886, was an equatorial refracting telescope 

 with an 1 i-inch aperture Clark lens and a Warner & Swasey mount. 208 



Since their retirement from active service several Clark and Clark- 

 modified instruments have found their way into the Smithsonian In- 

 stitution — in the collections of the Division of Physical Sciences of 

 the United States National Museum — where they are being preserved 

 and are available for study and exhibition. Of the Transit of Venus 

 apparatus the museum has acquired the 7-inch plane mirror (cat. 

 #327,709), the 5-inch achromatic objective (cat. #327,710), and the 

 jaw micrometer (cat. #327,708) used on Kerguelen Island. From the 

 U.S. Naval Observatory the museum has received the Merz und Mahler 

 comet seeker (cat. #327,700) and the 9.6-inch Merz und Mahler ob- 

 jective (cat. #327,703), both of which the Clarks refigured. Vassar 

 College has given the museum the 12 -inch equatorial refractor made 

 originally by Fitz and remade by the Clarks and Warner & Swasey 

 (cat. #323,566). The original Warner & Swasey equatorial mount, 

 from the telescope of Beloit College, is also in the museum (cat. 

 #316,100). The most recent addition to the Smithsonian's collection 

 is the spectroscope made by the Clarks in 1877 for Princeton University 

 (cat. #328,611) (see fig. 23, p. 96). 



The Jesuit Stonyhurst College, near Clitheroe, East Lancashire, 

 England, has the Clark equatorially-mounted refracting telescope which 



207a j us t us M. Silliman, "On the Examination of the Bessemer Flame with 

 Colored Glass and with the Spectroscope," American Journal of Science, vol. 50 

 (1870), pp. 301-302. 



208 William C. Winlock, "Astronomy for 1886," Annual Report . . . Smithsonian 

 Institution . . . i88y, p. 155. 



90 



