fractor previously owned by D. W. Edgecomb and Charles P. Howard 

 (qq.v. ). According to Bourne this 2-inch aperture instrument resolves 

 well within the Dawes limit, and its surfaces are accurate to about 1/20 

 of a wavelength. 



The Clark lenses retained their value for many years, and a used lens 

 was often as highly prized as a new one. In 1856 Frederick Brodie, in 

 England, replaced his 6 5/3 -inch Munich refractor with a Clark objective 

 of 7 1 /) inches aperture. 1 " This was the first lens which Clark had sold to 

 Dawes (q.v. ) ; in 1873 it was installed in the private observatory of Went- 

 worth Erck (q.v.). 



Addison Brown, amateur astronomer, used his 4-inch Clark refrac- 

 tor, mounted on a tripod, to view the total solar eclipse of 1878. 23 



One of the last large instruments made completely by the Clarks was 

 the 10-inch equatorial at Bucknell College in Lewisburg, Pennsyl- 

 vania. 24 This instrument, installed in 1887, is still in use. 25 It was pro- 

 vided with 5 common eyepieces, a polarizing eyepiece for solar observa- 

 tions, a micrometer, and a 2/2 -inch finder. The right ascension and 

 declination circles were read with small telescopes. The observer could 

 regulate the driving clock — which was changed only a few years ago — 

 at will and move the telescope with handles without leaving the eyepiece. 



The most productive and famous small Clark telescope was the 6-inch 

 refractor made for Sherburne Wesley Burnham in 1870. With this 

 instrument Burnham began his study of the heavens and discovered sev- 

 eral hundred double stars, many of which had been missed by more prac- 

 ticed astronomers with much larger telescopes. 26 In 1881 this 6-inch was 

 mounted in the Students' Observatory at the University of Wisconsin 

 (q.v.). 



Jacob Campbell, a New York City banker, owned a 12-inch equa- 

 torial refractor made by Henry Fitz. As they did with so many of the 



22 Frederick Brodie, "Notes on the Manufacture of Tubes for Refracting Tele- 

 scopes," Monthly Notices, Royal Astronomical Society, vol. 17 (1856- 1857), p. 33. 



23 U.S. Naval Observatory Reports of the Total Solar Eclipses of July 2g, 1878, and 

 January 11, 1880 (Washington, D.C., 1880), p. 142. 



24 W. C. Bartol, "The Observatory's Equipment," The University Mirror (May 

 1887), pp. 100-101. 



25 From private correspondence with Robert R. Gross, Bucknell University 

 Archivist. 



29 Letter from S. W. Burnham, English Mechanic, vol. 13 (1871), pp. 488-489. 



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