128 REPORT — 1897. 



TJie Ai^plication of PJiotography to the Elucidation of Meteorological 

 Phenomena. — Seventh Report of the Committee, consisting of Mr. 

 G. J. Symons (Ghaii-man), Professor E. Meldola, Mr. J. 

 HoPKiNSON, Mr. H. N. Dickson and Mr. A. W. Clayden {Secre- 

 tary). (Brawn up by the Secretary.) 



The work of the Committee has been continued during the past year, 

 especially with regard to the measurements of cloud altitudes by means of 

 photography. A considerable number of the results given in the report 

 for 1896 have been verified by repeating the reduction of the plates. 



In order to afford an efficient check upon the accuracy of last year's 

 results, the altitude and azimuth of the sun were calculated by a different 

 method and the altitude of the cloud deduced from a fresh set of co- 

 ordinates measured on the plate. 



In no case did the new determination differ more than about 3 per 

 cent, from the old one, and in the majority of cases the agreement was 

 very much closer. Particular attention was given to the instances in 

 which the clouds had been determined to be floating at unusually great 

 altitudes, and there is no doubt that those determinations are substantially 

 correct. 



During the last nine months it has not been possible to keep up a 

 continuous series of photographs. The excessive rainfall of the early part 

 of the year transformed the level ground between the camera stands and 

 around one of them into a series of muddy pools, so that work was impractic- 

 able. But with this exception exposures have been made whenever 

 opportunity offered, and the stock of negatives has been largely increased. 



None of these additions have yet been reduced. The time available 

 for the observations is limited, and it has been thought better to accumu- 

 late negatives during the finer part of the year and reserve them to be 

 reduced in the winter, when opportunities for making observations are 

 rare. 



The warping of the ebonite shutters of the cameras has again proved 

 troublesome, and steps have been taken to get them replaced by similar 

 pieces of aluminium, a change which will probably be effected before this 

 report is presented. Some delay was also caused by the mischievous 

 behaviour of some unknown persons, who, on .Tune 22, amused themselves 

 by breaking the connecting wires and endeavouring to upset one of the 

 camera stands. 



Leclanche cells of the ordinary pattern have been substituted for the 

 faulty dry cells formerly used, and have given complete satisfaction. 



There is a good stock of plates in hand, and the photographs will be 

 continued during the summer. 



No fresh departure having been made, and the current expenses not 

 being heavy, the grant made at Liverpool has not been drawn. 



The work of the Committee being now limited to the investigation in 

 the hands of the Secretary, who will continue it at his own expense, no 

 grant in aid is asked, but the Committee would wish to be reappointed 

 for another year. 



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