588 LECTURE LX. 



existence of animal electricity. This industrious and ingenious philo- 

 sopher has the sole merit of the invention of the pile or battery, which has 

 rendered every other mode of exciting the galvanic action comparatively 

 insignificant. 



No sooner was Volta's essay communicated to the Royal Society, than 

 a pile was constructed by Mr. Carlisle, and its singular effects in the 

 decomposition of water were jointly observed by himself and Mr. Nichol- 

 son. The original existence of animal electricity, as asserted by Galvani 

 and Volta, has been in some degree confirmed by the experiments of 

 Aldini, the nephew of Galvani. A number of detached observations, of 

 considerable merit, have also been made by Pfaff, Ritter, Cruikshank, 

 Wollaston, Fourcroy, and many other chemists, both in this country and 

 on the continent. But Mr. Davy's late experiments must be considered 

 as exceeding in importance every thing that has been done upon the subject 

 of electricity, since the discovery of the pile of Volta. The conclusions 

 which they have enabled him to form respecting the electrical properties 

 of such bodies as have the strongest tendencies to act chemically on each 

 other, and the power of modifying and counteracting those tendencies 

 which the electric fluid possesses, have greatly extended our views of the 

 minute operations of nature, and have opened a new field for future inves- 

 tigations. I hope that I shall be pardoned by astronomers for having 

 inserted, on this occasion, in a vacant space among the constellations, in 

 the neighbourhood of Pegasus, the figure of a galvanic battery ; which 

 must now be allowed to have as great pretensions to such a distinction as 

 the electrical machine and the chemical furnace. 



The late experiments and speculations of Mr. Dalton, on various sub- 

 jects, belonging to different branches of physics, have tended to place some 

 parts of the science of meteorology in a new light. It is true that many 

 of his hypotheses are very arbitrarily assumed ; some of them are mani- 

 festly contrary to experiment, and others to analogy and probability ; at 

 the same time his remarks appear in some cases to be either perfectly cor- 

 rect, or to lead to determinations which are sufficiently accurate for every 

 practical purpose. I have attempted to borrow from Mr. Dalton' s ideas some 

 hints, which I have incorporated with a less exceptionable system ; and by 

 a comparison of his experiments with those of many other philosophers, I 

 have deduced some methods of calculation which may perhaps be practi- 

 cally useful ; in particular a simple rule for determining the elasticity of 

 steam, and a mode of reducing the indications of hygrometers of different 

 kinds to a natural scale. 



Count Rumford's establishment of a prize medal, to be given every three 

 years by the Royal Society to the author of the most valuable discovery 

 respecting heat or light, forms an era less remarkable, than the first adjudi- 

 cation of the medal to himself, and the second to Mr. Leslie. Count 

 Rumford's numerous experiments on the production and communication of 

 heat are highly important, both for the utility which may be derived from 

 their economical application, arid for the assistance which they afford us in 

 the investigation of the intimate nature of heat. Mr. Leslie's discovery of 

 the different properties possessed by surfaces of different kinds, with regard 



