In 1 882 the Clarks made a long focus — about 8 feet — lens, and perhaps 

 the mechanical parts as well, for a Littrow-type spectroscope for C. F. 

 Brackett of the Princeton physical laboratory. This economical and con- 

 venient instrument used the same lens and tube for both the collimator and 

 the viewing telescope. By a wise choice of curves, and the addition of a 

 small central screen, the usual problem of diffuse light reflected from the 

 lens surfaces was sufficiently reduced that the spectroscope was, in 

 Brackett's opinion, equal to any of the ordinary, two-telescope construc- 

 tion. 196 



Carr Waller Pritchett, founder and director of the Pritchett School 

 Institute in Glasgow, Missouri, searched for many years for support 

 for an astronomical observatory. Around 1867 he made plans for an 

 observatory to be erected on the institute grounds, and asked the Clarks 

 to make an 8-inch equatorial refractor. This instrument was actually 

 completed before "unforeseen difficulties" forced Pritchett to cancel the 

 order. 197 



In 1874 Pritchett found a reliable patron, in the person of Miss 

 Berenice Morrison, and was able to build and equip the Morrison Ob- 

 servatory (q.v. ) and use it in conjunction with his school. When the 

 Pritchett School Institute was closed in 1922, the observatory was trans- 

 ferred to Central College (q.v.). 



The third Clark objective larger than any yet made was mounted by 

 the Repsolds for the Russian observatory at Pulkowa. In honor of the 

 excellence of this instrument Alvan Clark and Georg Repsold received 

 gold medals from Czar Alexander III. 



Otto Struve had visited Cambridgeport in the summer of 1879 and, 

 in spite of the modesty of their shop, he contracted with the Clarks for 

 the 30-inch lens. He also insisted on paying an extra $1000 — a figure 

 George Clark thought much too high — for a rough equatorial mount 

 for testing the objective ; this mount later served for testing the Lick lens. 198 



The achievement of the Pulkowa lens inspired many expressions of 

 American national pride. Just twenty years previously, during the Civil 

 War, J. M. Gillis had struggled to equip the navy with American-made 



196 C. F. Brackett, "Note on the Littrow Form of Spectroscope," American Journal 

 of Science, vol. 24 (1882), pp. 60-61. 



197 Publications, Morrison Observatory, vol. 1 (1887), P- I - 



198 ^um 50-Jahrigen bestehn der Nicolai-Hauptsternwarte (St. Petersburg, 1889), pp. 

 25-38. 



86 



