1823.] Royal Society. 463 



from coming into immediate contact with its sides. Above this 

 closed cylinder was fastened another, full of perforations, to 

 allow the water free passage through it, and likewise furnished 

 with a thermometer. The line was let out in twenty-five minutes; 

 and, by the lowest estimation, 1000 fathoms, or 6000 feet, was 

 the perpendicular depth to which the cylinders descended : it 

 was drawn back in fifty-three minutes, when, owing to the cir- 

 cumstance that the top of the closed cylinder had not been 

 screwed down sufficiently upon the leather, the sea was found 

 to have entered it ; in this, the thermometer marked 49 , 5°, and 

 that in the perforated cylinder 45-5° ; the temperature of the 

 surface of the sea was from 82° to + 83°, so that the difference 

 of its temperature there, and at the depth above-mentioned, 

 amounted to + 37°. 



Capt. Sabine inferred from this result, that at a depth little 

 exceeding that at which the experiment was made, the sea- 

 water would be found to have attained its greatest density, sup- 

 posing that point to be, as in fresh-water, a i'ew degrees above 

 the freezing point. He terminated the communication by some 

 remarks on an experiment made by Peron, the result of which, 

 as far as it was satisfactory, agreed with his own. 



At this meeting, likewise, the reading was commenced of 

 A Continuation of Prof. Buckland's Account of the Bones dis- 

 covered in Caves in various Parts of England. 



April 24. — An Account of Experiments made to determine 

 the Length of the Invariable Pendulum at various Places on the 

 South American Station. By Capt. Basil Hall, FRS. in a letter 

 to Capt. Kater, FRS. 



The places at which Capt. Hall had ascertained the Length of 

 an Invariable pendulum belonging to the Board of Longitude, as 

 detailed in this paper, were the following : The volcanic island 

 of Abingdon, one of the Gallapagos ; the sea-port of San Bias on 

 the coast of Mexico ; and Rio de Janeiro on the coast of Brazil. 

 He stated, among various other circumstances, that he had 

 unsuccessfully endeavoured to simplify Capt. Kater's method of 

 determination ; and he intimated that he purposed to make some 

 experiments on the actual effects of heat upon the pendulum, 

 independently of all theoretical considerations. 



May 1. — On the Expansion by Heat of Gases in various 

 States of Condensation and Rarefaction, being an Appendix to 

 a former paper on the Application of the Gases, condensed into 

 Liquids, as Mechanical Agents. By Sir H. Davy, Bart. PRS. 



The experiments of MM. Gay-Lussac and Dalton have 

 shown, that the gases expand equally for equal increments of 

 heat, at all temperatures between 32° and 212°; but the Presi- 

 dent was not aware that any direct experiments had been insti- 

 tuted with the view of determining whether the same law 

 prevailed with regard to the respective aeriform bodies at differ- 



