216 



Report of the Kew Committee. 



Old Solar Observations. — The library of the Observatory has 

 received a present from Wm. J. Davies, Esq., of a MS. volume of sun- 

 spot observations made at Edmonton, Middlesex, from August, 1819, 

 to March, 1 1823. It is intended to enumerate the spots after the 

 Schwabe method, so as to carry the Observatory catalogue of the new 

 groups of sun-spots back to 1819. 



Kew Solar Photographs. — At the request of the Chairman, the MS. 

 sun-spot measurements and reductions from February, 1862, to 

 December, 1863, together with the tables for computing the spotted 

 positions, as well as the Kew working catalogues from 1864 to 1872, 

 have been forwarded to Mr. A. L. Soper for the purpose of further 

 discussion. 



IV. Experimental Work. 



Photo-nepho graph. — The cameras used in cloud photography having 

 been put in order, and had new adjustable rapid shutters fitted, were 

 again brought into use, and by request of the Meteorological Council 

 24 sets of photographs comprising 90 negatives were taken on 14 

 days, chief attention being directed to the photographing of high cirrus 

 clouds. 



Prints of all the pictures have been made on cyanotype paper, 

 which together with the observational data have been transferred to 

 the Meteorological Office for the reduction and computation of cloud 

 heights and velocities, Professor Stokes's cloud projection apparatus 

 having also been transferred there for the purpose. 



Solar Radiation. — The observations of the black bulb thermometers 

 in vacuo made during 1886 were reduced and discussed, and the 

 results found to be no more satisfactory than those obtained in pre- 

 vious years, the vacua in all of the instruments having deteriorated^ 

 and their readings having become lowered during the time they were 

 under observation, whilst the readings differed considerably amongst 

 themselves. 



The Chairman having undertaken to submit the tubes to a lengthy 

 exhaustion, three instruments were fitted with new jackets and sealed 

 on to the air-pump in his laboratory. 



They were there exhausted almost daily, the atmospheric pressure 

 "being reduced to and maintained at about 0'06 |V| from April to the end 

 of September. On October 1st they were removed from the laboratory 

 and replaced on the stand at the Observatory, having been read daily 

 ever since. 



Large differences are still found to exist in the readings of the 

 similar and similarly placed instruments. 



Pendulum, Experiments. — The Indian Pendulum Apparatus, returned 

 from the United States by Professor Peirce, was put up in the pen- 

 dulum room specially erected for its accommodation in the South Hall 



