48 REPORTS ON THE STATE OP SCIENCE.— 1915. ] 



discussion following upon the reading of tlie last Eeport of the Com- 

 mittee in Melbourne, which was reported in the Australian papers ; and 

 by a vigorous reply to a newspaper criticism by the Chairman. The 

 Committee also wishes to draw attention to the valuable report upon the 

 site of the Observatory at Canberra written by Mr. Baracchi, of which a 

 brief account was read to the Association in Melbourne. 



Though the war will necessarily delay the institution of the Solar 

 Observatory at Canberra, the Committee trusts that its efforts have 

 met with a measure of success. 



Determination of Gravity at Sea. — Interim Report of the Com- 

 mittee, consisting of Professor A. E. H. Love {Chairman), 

 Professor W. Gr. Duffield (Secretary), Mr. T. W. 

 Chaundy, Sir F. W. Dyson, Professor A. S. Eddington, 

 and Professor H. H. Turner. (Drawn up by the Secretary.) 



It was decided by the Committee of Section A that advantage should 

 if possible be taken of the voyage to Australia for the 1914 Meeting 

 of the British Association to undertake a series of observations upon 

 the determination of the value of gravity over the ocean. The main 

 object of the research was to test the compensation theory, or theory 

 of the isostatic layer, in regard to the distribution of matter in the 

 superficial portions of the earth. The Secretary to the Committee 

 undertook to make an attempt to solve the problem, and upon the 

 advice of the Chairman wrote to Professor Hecker, who had previously 

 undertaken some important researches in this respect. 



Professor Hecker advised that six months' preparation would be 

 insuflicient to enable an experimenter to accumulate the apparatus and 

 become au fait with the technique of the method which he had em- 

 ployed in 1901 and 1904 — i.e., the comparison of a mercurial barometer 

 with a boiling-point apparatus for determining the atmospheric pres- 

 sure. But after consultation with Professor Helmert he invited the 

 Secretary to test a new piece of apparatus which he had had constructed 

 for the determination of gravity at sea, and which he had not previously 

 had the opportunity of testing. This depends upon balancing a column 

 of mercury against air enclosed in a vessel and maintained at a con- 

 stant temperature. The Secretary regretfully accepted Professor 

 Hecker 's dictum concerning the undesirability of attempting to repeat 

 the experiments by the boiling-point method, but gratefully accepted 

 his offer of the opportunity to test the new piece of apparatus. A feature 

 of the new method being the constancy of the temperature of the air 

 reservoir, it was necessary to carry out the experiments in the refrigera- 

 tor of a vessel. The Secretary was fortunate in obtaining the permis- 

 sion of Messrs. Alfred Holt & Co., of the Holt Line of steamships, to 

 make use of the refrigerator on board the Steamship Ascanius, which 

 was sailing from Liverpool on June 22, 1914. By invitation, he in- 

 spected the refrigerating chambers on a sister ship, as the Ascanius 



