O.N i'HE UETElUliNATlON OF GRAVITV AX SKA. -jGo 



a long series of observations as siiperposed upon other and larger effects 

 due to temperature eluinges, and in the same way differences between 

 coastal and inland gravity values might 1)C looked fur in the average 

 yearly barometric pressures. 



13. Conclusion. 

 In conclusion this paper is intended to be an examination of a parti- 

 cular method of measuring gravity at sea, and docs not claim more than 

 that it shows the limitations of" the method. I think, however, that 

 from these preliminarv observations it may be confidently asserted that 

 the general deviation "of gravity from the theoretical value over oceans 

 of depth of 6000 metres is not of greater order of magnitude than 0-3 

 cms. /sec.'-, i e. 8g/g :^ 3xl0~*. Certain divergences have been found; 

 it cannot be definitely asserted that they are real. Nevertheless, in view 

 of the difficulties of a research of this nature, the results have been given 

 in some detail in the hope that subsequent researches will benefit by 

 their discussion, and that the problem of the distribution of the material 

 of the earth's crust may be carried a step nearer solution. 



Such evidence as has been adduced points to a defect of gravity over 

 deep oceans ; there is also some evidence that there is a defect of gravity 

 on the edge of a continental mass, especially if there is a coastal mountain 

 range, and that gravity has higher values over island stations than over 

 deep seas. 



Id the luteriiu Report (B. A. Report, 1915) the Committee has ex- 

 ]u-essed its thanks to the Directors of the Blue Funnel and the P. & 0. 

 lines of steamships, and to the captains and officers of ss. Ascanius and 

 R.M.S. Moira, for assistance in installing the apparatus and in arranging 

 for the conduct of the experiments. In addition to those who have already 

 l)een mentioned, the experimenter is indebted to IMr. William Haddow, 

 officer of ss. Ascanius, for workhig out the ship's positions at the times 

 when the observations were taken, and to Sy. Chief Officer Sandberg, 

 of R.M.S. Morea, for similar services on the return voyage. 



Mr. Chaundy assisted in the reduction of the preliminary observations 

 on ss. Asmnius, but the bulk of the reductions on both voyages were 

 carried out by Miss C. Mallinson, B.Sc. of University College, Reading, 

 under the supervision of the Secretary. 



Mr. F. J AV. Whipple, of the Meteorological Office, has been consulted 

 upon a number of occasions upon points which have arisen in connection 

 with this research, and in particular with regard to the determination of the 

 aneroid constant; the observations made at the Meteorological Office 

 were kindly carried out by him, and his help is gratefully acknowledged. 

 The two barometers used in this research were made by the Cambridge 

 Scientific Instiniment Company. The marine barometer had been presented 

 to the Meteorological Office, and it was with the Scientific Instrument 

 Company's consent that Sir Napier Shaw kindly placed this instrument 

 at the disposal of the writer. The aneroid was specially constructed 

 for this research and kindly lent to the experimenter. It is with very 

 much appreciation that the Secretary acknowledges his indebtedness 

 to the Cambridge Scientific Instrument Company, and in particular to 

 Mr. Horace Darwin. It was due to this generous action that a test of 

 the aneroid method at sea was rendered possible. 



