66 Proceedings of Philosophical Societies, [July, 



the Society that have been made by the Council in their recent 

 revision of them ; by one of which, the meetings of the Society 

 will commence, in future, for each Session, on the first of the two 

 Thursdays preceding the Anniversary, and terminate on the 

 third Thursday in June. 



The Society then adjourned accordingly, to Thiirsdat/ the 

 20th of November next. 



A paper on the Compressibility of Water, Air, and other 

 Fluids ; and on the Crystallization of Liquids, and the Lique- 

 faction of Aeriform Fluids, by simple pressure, w as prepared 

 by Mr. Perkins, for the purpose of submitting it to the 

 Royal Society ; but it w^as accidentally misplaced, pre- 

 viously to the last meeting, and therefore could not be an- 

 nounced to the Society with the other papers. It contained, 

 we are informed, a minute description, accompanied with 

 figures, of his compressing apparatus ; a diaoram, showing 

 the ratio of the compressibility of water, beginnmg at the pres- 

 sure of 10 atmospheres, and proceeding regularly to that of 

 2000 ; and some experiments on the compression of atmospheric 

 air, which appears by them to follow a law varying from that 

 generally assigned to it by philosophers. Mr. Perkins intended 

 to announce, also, in this paper, that he had effected the lique- 

 faction of atmospheric air, and other gaseous substances, by a 

 Eressure equal to that of about 1100 atmospheres ; and that he 

 ad succeeded in crystallizing several liquids, by simple pres- 

 sure. 



ASTRONOMICAL SOCIETY. 



Mai/ 9. — At this meetincr, a paper on the Mercurial Compen- 

 sation Pendulum, by Francis Baily, Esq. FRS. was read, but 

 owing to its length, it could not be completed. 



June 13. — ^The reading of Mr. Baily's paper on the Mercurial 

 Compensation Pendulum was resumed and concluded. It con- 

 tains an account of many experiments made to determine the 

 rates of expansion of the various substances used in the construc- 

 tion of such pendulums, the results of which are given in a 

 tabular form'. The expansions of mercury, as given by different 

 authors, are collected, and it is shown that none of them can be 

 safely applied to the purposes of the pendulum without certain 

 modifications which are pointed out in this paper. The princi- 

 ples of the Compensation Pendulum are then mvestigated, and 

 a formula deduced for determining the height of the quicksilver 

 in the cylinder, the result of which is different from those given 

 by preceding writers on this subject. Mr. Baily then points out 

 some improvements in the usual mode of constructing and regu- 

 lating pendulums, which appear very simple and efficacious ; and 

 concludes his paper by the description of a compensation pendu- 



