ON PUOTOaRAPIIS OF METEOROLOGICAL PHENOMENA. 77 



Second Report of the Gommittee, consisting of Mr. Gr. J. Symons 

 (Chairman), Professor R. Meldola, Mr. J. Hopkinson, and Mr. 

 A. W. Clatden (Secretary), appointed to consider the applica- 

 tion of Photography to the Elucidation of Meteorological 

 Phenomena. (Drawn up by the Secretary.) 



Tour Committee report tliat the work has been continued daring the past 

 year on the lines laid down in the Report for 1891. 



Considerable additions have been made to the number of observerp 

 from whom assistance may be expected, in spite of the removal of several 

 names from last year's list. 



The total number of photographs received up to July 23 was 361, 

 representing a variety of phenomena, but chiefly illustrating the results 

 obtainable in cloud photography by various methods. This number, 

 however, does not adequately represent the progress made, for many 

 other photographs have been promised, and will in all probability be 

 received in a few weeks. 



The adoption by the majority of the International Meteorological 

 Congress at Munich of the classification of clouds, proposed by Messrs. 

 Hildebrandson and Abercromby, suggested to your Committee that it 

 would be well for them to adopt it, at least provisionally. They cordially 

 agree with the action of the English delegates at the Congress in 

 opposing the acceptance of a system which is entirely empirical ; bul 

 since the great majority of foreign meteorologists have determined to 

 employ it, your Committee consider that they should adopt it provision- 

 ally. They think it will be well to follow the example set by other 

 countries until the further study of cloud-forms, and their relation to one 

 another, render it possible to make a more scientific code. 



Arrangements have therefore been made for the cataloguing of the 

 collections of meteorological photogi'aphs in the possession of the Royal 

 Meteorological Society, and of the Chairman of your Committee. 



Photographs of Lightning. 



Very few new photographs have been sent in as yet, but from Mr. 

 J. H. Bateman two of great interest have been received. Following the 

 suggestions in the instructions issued last year, two cameras were em- 

 ployed, the first being stationary, and the second moved rapidly from 

 side to side. The plate exposed in the fixed camera shows four flashes, 

 while the one which was moved shows six. A flash which is single or 

 the fixed plate is resolved into three on the moving plate, showing that 

 the flash did consist of a series of discharges along much the same path. 

 The absence of reduplication in the others points to the conclusion that 

 they were single. Two of these single flashes occupy exactly the same 

 relative positions on the two plates, showing that they must have been 

 simultaneous. 



Your Committee regret that there should have been no opportunity of 

 carrj'iiig out any further experiments upon the phenomena presented by 

 lightning photographs. However, recent discoveries concerning high- 

 tension discharges ought to elucidate the subject. Thus it seems highly 

 probable that the hazy continuous luminosity shown by many photo- 

 graiihs may be due to the flame of burning nitrogen. ^ 



Before leaving the subject of lightning, it may be pointed out that in 



