EEPOETS 



ON THE 



STATE OF SCIENCE. 



Report of the Comtnittee, consisting of Professor Sir William 

 Thomson, Professor Tait, Professor Grant, Dr. Siemens, Pro- 

 fessor Purser, Professor G. Forbes, Mr. Horace Darwin, and 

 Mr. Gr. H. Darwin {Secretary'), appointed for the Measureonent 

 of the Lunar Disturbance of Gravity. 



The Committee beg leave to report as follows : — 



The sum of £30 granted in 1879 for the purposes of the Committee 

 has been paid to Mr. G. H. Darwin. 



Before the meeting of 1879 Mr. G. H. Darwin and Mr. Horace Darwin 

 were making prepo-rations for carrying out experiments with a view of 

 detecting sm.all variations in the directions of the force of gravity. With 

 the aid of the above grant some preliminary experiments have been made 

 during the past year by Mr. G. H. and Mr. H. Darwin in the Cavendish 

 Laboratory of the University of Cambridge by means of an instrument of 

 which the jjrinciple was suggested to the experimenters by Sir William 

 Thomson. 



The experiments have not as yet been carried sufi&ciently far to make 

 it desirable to present a detailed report to the British Association. It 

 may nevertheless be mentioned that results of some interest have been 

 attained with regard to the warping of stone columns under the influence 

 of minute changes of temperature or of small stresses. 



The chief conclusion, however, to which the experimenters have been 

 led is that it is now necessary to entirely re-design the apparatus. It seems 

 probable that the experiments will occupy a considerable time, and may 

 possibly prove expensive. 



Under these circumstances the Committee think it expedient to defer 

 the presentation of their Report and of the accounts until the meeting of 

 the Association in 1881. 



Supplementary Report. 



The Secretary of this Committee having got in and paid an outstanding 

 account since the Report was sent in, finds that nearly the whole sum 

 granted for the purposes of the Committee in 1879 has been expended. 



