1879.] 



Presidents Address. 



417 



or arcs of parallels of latitude, in different places ; the other by mea- 

 suring by means of the pendulum the variation of gravity from place 

 to place, from whence the figure of the earth may be deduced by an 

 extension of Clairaut's theorem. 



"Avery elaborate investigation of the problem as deduced from 

 geodetic measurements has been made within the last few years by 

 our Fellow Captain (now Colonel) Clarke, R.E., in connexion with the 

 great Trigonometrical Survey of the United Kingdom, but including 

 results of the geodetic operations, so far as they bear on this problem, 

 undertaken by other nations and in other parts of the world. 



" The results as to the figure of the earth, deducible from pendulum 

 observations that had been then executed, were discussed by the pre- 

 sent Astronomer Royal in an article published in the ' Encyclopaedia 

 Metropolitana.' But thirty years have passed since the publication 

 of that work, during which time very important contributions to our 

 knowledge of the variation of gravity over the earth have been made 

 by different nations. Among them the elaborate series that was 

 carried on in connexion with the great Trigonometrical Survey of 

 India occupies a prominent place. It appears, therefore, very de- 

 sirable that the conclusions deducible from our present stock of 

 pendulum observations should be exhaustively discussed." 



Major Herschel is on his way to England, to carry out the proposed 

 work. 



(5.) The Publications of the Society. — The Catalogue of Scientific 

 Papers. — The second volume of the supplementary decade, viz., 1863- 

 73, has been brought to a close, and copies are now in the hands of 

 the Fellows and the public. It exceeds in bulk any of the earlier 

 volumes of the work, and extends to 1,310 pages. In this supplement, 

 313 additional scientific serials have been catalogued, making the 

 total of such serials now comprised in the whole no less than 1,938. 

 The donation list for this volume has been the same as that for 

 former volumes, with the addition of a few Societies and Institutions 

 sanctioned by the Treasury at the recommendation of the Council. 

 The Fellows have the right to purchase the supplement at the same 

 reduced price per volume as the original work. The Council has 

 authorised the preparation of titles for another decade ; and some 

 progress has already been made in the work. 



Apart from the Catalogue of Papers, the main strength of the 

 Library of the Royal Society consists in its collection of the publica- 

 tions of scientific Academies, and Societies, and of scientific journals, 

 unrivalled anywhere in this country, except perhaps in the British 

 Museum. It has always been held that the first duty of the Library 

 Committee is to maintain, and wherever possible to increase, our 

 efficiency in this respect. As regards our general collection of books, 

 the Committee and Council are of opinion that it will be best to 



