( 6i2 ) 

 » En opérant de la même manière, on obtiendra pour la développante 

 oblique troisième 



(6) 





sin'^a-r» 



4200 



G 

 4307 



AiR 



000000 



DISCOVEET OF OXTaEN Hf THE SUlî BT PHOTOORAPHT, BY PBOFESSOa HENBT DRAPES. M. D, 1876. 



The upper part of the photograph is the spectrvrm of the Sun, the lower part is the spectrum of the Oxygen and Nitrogen of Air. The lettera and flgnrea on the 

 margin are printed with type on the négative; with this exception the photograph is absolutely free from hand work or retouehing. O. indicates Oxygen, N. 

 Nitrogen, Te. Iron, Al. Aiuminium. Tne figures above the Sun's spectrum are wave lengths: G. h. H., are prominent Solar Unes at the violet end of the 

 spectrum'. The principal point to examine is the coïncidence of the bright Oxygen Une» with bright Unes in the Solar spectrum. The pioture ia printed from 

 Draper's original négative by Bierstadt's Albertype process. 



