80 REPORT — 1895. 



find that if the greatest care be taken in the manufacture of the wooden 

 box and the metalUc adjuncts which are close to the magnet the discre- 

 pancies disappear. 



In other words, the cause of the difficulty, in these three instruments 

 at all events, is, not the metal base, but the much smaller masses of metal 

 which are nearer to the magnet. 



The three magnetometers are now in good accord. 



A week has been spent at each of four observatories for the purpose 

 of comparing one of these magnetometers and a dip-circle with the obser- 

 vatory instruments. Professor Riicker made the observations at Kew 

 and Falmouth ; Mr. "Watson, those at Stonyhurst and Valentia. 



The greater part of the work which the Committee undertook has thus 

 been accomplished. 



It is still necessary to compare the instruments again witli the instru- 

 ments at Kew to ascertain that they are unaltered by transfer from one 

 place to another ; and as a new magnet-house is about to be built at 

 Greenwich, it has been thought better to postpone the comparisons at 

 that observatory until the house is ready for use. 



The reductions of the observations which have been made are not yet 

 finished. A full report will be made when the work is completed. 



The Committee therefore ask to be reappointed, but no further grant 

 is required. 



The Amplication of PJiotography to the Elucidixtion of Meteorological 

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

 G. J. Symons (Chairman), Professor R. Meldola, Mr. J. 

 HOPKIXSOX, and Mr. A. W. Clavden (Secretary). (Drawn xip by 

 the Secretary.) 



In the report which the Committee presented last year, it was proposed 

 that an agreement should be entered into with the London and South - 

 "Western Railway Company for the use of a site on their land, in order to 

 carry out some measurements of cloud altitudes by means of photography. 



This has been done. The cameras have been placed in position, and 

 almost the whole time at the disposal of the secretary for such purposes 

 has been spent in perfecting the electrical connection for releasing the 

 two shutters simultaneously. Considerable trouble has been experienced 

 in doing this. The appai'atus, which worked admirably over a short dis- 

 tance, proved unreliable over the greater distance (200 yards) at present 

 adopted. The agreement with the railway company provides that the 

 connecting wire shall be removed when not in actual use, thereby 

 necessitating as light a wire as can be made to suffice, which of coui'se 

 implies a considerable resistance. The result is that a more sensitive 

 electric detent is required for the shutters, especially as it seems not 

 unlikely that the distance may have to be increased by another 100 yards 

 when the measurement of the highest varieties of cloud is attempted. 

 This is still engaging the attention of the secretary to the Committee. 



Some observations have been made, but although they confirm the 

 belief that the method will prove valuable they have not yet been reduced 

 to actual measurements. It .should be remembered that the method is 

 only applicable to those varieties of cloud which are visible at the same 

 time as the sun, and that the opportunities of making observations cannot 



