THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



MARCH 1881. 



XXIII. On the Phosphorograph of a Solar Spectrum, and on 

 the Lines in its Infra-red Region. By John William 

 Draper, M.D.. Professor of Chemistry in the University of 

 JS r eio York*. 



I PROPOSE in this communication to consider (1) the 

 peculiarities of a phosphorograph of the solar spectrum 

 as compared with a photograph of the same object ; (2) the 

 antagonization of effect of rays of higher by those of lower 

 refrangibility. 



There is a striking resemblance between a photograph of 

 that spectrum taken on iodide of silver and a phosphorograph 

 taken on luminous paint and other phosphorescent prepara- 

 tions. There are also differences. 



I. Description of the Photographic Spectrum. 



In 1842 I obtained some very fine impressions of the first 

 kind (on iodide of silver), and described them in the Philo- 

 sophical Magazine, November 1842, and again in February 

 1847. One of these was made the subject of an elaborate 

 examination by Sir J. Herschel. His description and expla- 

 natory views of it may be found in that journal, Februarv 

 1843.' 



From these it appears that such a photograph, taken in pre- 

 sence of a weak extraneous light, may be considered as pre- 



* Read "before the American Academy of Arts and Sciences, and 

 communicated by the Author. 



Phil. Mag. S. 5. Vol. 11. No. 67. March 1881. N 



