VII. PHOTOGRAPHY. 425 



1917c. Photograph of the Sun, taken by Professor Win- 

 lock, by a simple lens of 40 feet focal length. 



J. Norman Lockyer, F.R.S. 



1863a. Photographic Normal Spectrum of the Sun. 



Collection of enlarged comparison photographs, used in the 

 research. J. Norman Lockyer, F.R.S. 



1863b. Photograph of the Solar Spectrum, showing its 

 absorption lines, by George Rutherfurd, of New York. 



Robert James Mann, M.D. 



The entire blue part of the spectrum is divided into sections, which are 

 mounted above each other. When these are placed together in their proper 

 continuation, the spectrum is nearly 8 feet long. 



1863c. Photographic reproduction of the Solar Spec- 

 trum in its natural colours. First proofs obtained by M. E. 

 Becquerel in 1848. (This proof, enclosed in a box, must be pro- 

 tected from the light.) M. E. Becquerel. 



1864. Photographs of the less refrangible parts of the sun's 

 spectrum, from line E downwards, and photographs of a larger 

 spectrograpb, which, being in use, could not be spared for this 

 exhibition. Prof. II. W. Vogel, Berlin. 



The accompanying photographs of the solar spectrum had been taken on 

 silver chloride and bromide, which had been made sensitive to the less 

 refrangible rays through addition of light-absorbing media. 



1864a. Sun spots photographed at Wilna with Dallme- 

 yer's Heliograph. The Observatory, Wilna. 



These photographs are made with the Dallmeyer heliograph, constructed for 

 the Observatory of Wilna, on the designs of De la Rue. Six of these belong 

 to the period of maximum of sun spots in September 1870, 12 other represent 

 the largest sun spots observed during the years 1871-1875. Similar photo 

 graphs are made at Wilna every bright day, under the direction of Colonel 

 Smysloff, for promoting the study of the surface of the sun. 



1865. Photographs of different parts of the Sun's 

 spectrum. Dr. IT. C. Vogel and Dr. Osw. Lohse, Potsdam. 



1866. Photographs of the Sun. 



Dr. H. C. Vogel and Dr. Osw. Lohse, Potsdam. 



1867. Photographs of Jupiter. 



Dr. H. C. Vogel and Dr. Osw. Lohse, Potsdam. 



1868. Drawing of the Spectrum of the Sun between 

 Fraunhofer's lines Hj and H 2 , made from a photograph. 



Dr. H. C. Vogel and Dr. Osw. Lohse, Potsdam. 



