84 



Report of the Kew Committee. 



remains at the Observatory, but having been accidentally deranged, it 

 has not been at work for some months. The inventor being abroad it 

 has not been possible to place it in re-adjustment. 



Nephoscopes. — Experiments have been made with several forms of 

 nephoscope designed by Mr. F. Galton, and also with a new cloud- 

 camera, designed by the Superintendent. 



Exposure of Thermometers. — Experiments have been continued 

 throughout the year at the Observatory, with the view of determining 

 the relative merits of different patterns of thermometer screens. For 

 this purpose there were erected in 1879 on the lawn a Stevenson's 

 screen, of the ordinary pattern, and a large wooden cage, containing 

 a Wild's screen, of the pattern employed in Russia. Each of these 

 screens contains a dry and a wet bulb thermometer, and a maximum 

 and minimum, all of which are read daily at 9 a.m. and 9 p.m., their 

 indications being compared with those of the thermograph at the same 

 hours. A third portable metal screen, designed by Mr. De La Rue 

 for use on board Light- ships, which contains a dry bulb thermometer 

 only, is also carried into the open air by the observer, and read at the 

 same time as the fixed instruments. 



The cost of these experiments is borne by the Meteorological 

 Council. 



Glycerine Barometer. — This instrument, devised and erected by 

 Mr. Jordan, has remained in successful operation throughout the year. 

 In compliance with the request of the inventor, it has been con- 

 tinuously observed five times daily, in conjunction with the mercurial 

 barometer. 



Mr. Jordan has been supplied with copies of the observations, but 

 the Committee have not yet, however, been informed of the results 

 of these comparisons. 



Pendulum Experiments. — In March, the Committee received a 

 communication from the Council of the Royal Society, calling their 

 attention to the fact that the invariable pendulums deposited in the 

 Loan Collection of scientific instruments at South Kensington, could 

 not be considered as in the custody of the Committee, and in conse- 

 quence the Science and Art Department was requested to return the 

 instruments to the Observatory. They were accordingly received on 

 the 15th of June. 



Subsequently an application was received from Major Herschel, 

 R.E., F.R.S., by authority of the India Office, for permission to make 

 certain experiments with the pendulums, and for the loan of the 

 instruments, with their accompanying appliances, with facilities for 

 prosecuting the experiments at the Observatory. 



These requests were granted, and since the beginning of September 

 operations have been continuously carried on, both in the Pendulum 

 Room and in the Experimental House at Kew. 



