Intelligence and Miscellaneous Articles. 391 



This volume rivals the first in the object of elucidating the 

 History of the Earth ; for, as that gave the physical or inanimate 

 division of its history, this volume, enquiring in the first place 

 what possibly may have been the original condition of the Earth's 

 crust, euables us to note when Life first made its appearance upon 

 it, — to determine the character of that Life, and to follow its 

 development and successive modifications through all Greological 

 Time. 



Together with this study of Biological Evolution, the great 

 physical changes of the surface, the constant alterations in the 

 distribution of land and water, and the relation of these physio- 

 graphic changes to the distribution of Life on the land and in 

 the water are carefully noticed. 



Besides the illustrations of fossils in Volume II. numerous 

 diagrams of sections, views, plans, &c, as well as large maps enrich 

 each volume, and a full Index completes the work. 



XLIII. Intelligence and Miscellaneous Articles. 



PHOTOGRAPHY OF THE LEAST REFRANGIBLE PORTION OF THE 

 SOLAR SPECTRUM. BY J. C. B. BURBANK *. 



TT has been stated by eminent authorities that the process of 

 -*- staining dry plates with various dyes is not applicable to the 

 photography of the invisible rays beyond the red of the solar 

 spectrum. To test this question I have undertaken a series of 

 experiments with the dye cyanine. This dye has of late come into 

 considerable prominence in photography, owing to its orthochro- 

 matic effect when mixed with other dyes, such as chinoline-red, 

 azaline, erythrosine, and eosine. 



It was discovered by Greville Williams, an Englishman, in 1861 

 but did not come into much prominence until the year 1884, when 

 its usefulness as a sensitizer became more apparent. The dye is 

 easily decomposed by light, and even in the dark both its solution 

 and the plates coated with it are apt to become decomposed if 

 kept for any length of time. Alone, it has been found very useful 

 to sensitize plates for the orange and red portions of the spectrum. 

 No experiments have to my knowledge been made upon the effect 

 of heat-rays upon cyanine plates. 



The direct action of absorbents in the infra-red has not, hitherto, 

 been tried with any success ; moreover, it has been stated by so 

 eminent an authority as Captain AV. De W. Abney that it was 

 impossible to make plates sensitive to any rays below the A of the 

 solar spectrum by means of the addition of dyes to a film. It is 

 true, however, that Major Waterhouse has succeeded by means of 

 turmeric in obtaining evidence of the existence of a few lines on 

 the less refrangible side of A, but in all cases except one these 

 were reversed. 



The plates employed were made by the M. A. Seed Co. of sensi- 

 tpmeter 22. The method used in staining the plates and in the 



* From aD advance proof from the ' Proceedings of the American 

 Academy.' Communicated by the Author. 



