482 



heat increases, and while it is fasting it diminishes; but this dimi- 

 nution has a limit, whereas increased respiration is invariably attended 

 by increased heat. Gaseous matter is exhaled in great abundance 

 from the surface of the body of an insect, and contributes to regulate 

 and equalize its temperature; but the quantity diminishes in propor- 

 tion to the length of time during which it has been deprived of food. 

 The author maintains that animal heat is not an effect of mere 

 nervous influence, either general or ganglionic ; an opinion which he 

 derives from the following considerations : first, that in many insects 

 in which considerable degrees of heat are evolved, and the respira- 

 tion is energetic, the nervous system is small compared with that of 

 others in which the respiration is less vigorous ; and secondly, that if the 

 evolution of animal heat were dependent on the existence of ganglia, 

 the leech ought to generate more heat than the larva of the Lepi- 

 doptera, since it has a much greater number of ganglia. Hence he 

 is disposed to draw the general conclusion that animal heat results 

 directly from the changes which take place during respiration ; and 

 that the reason why so large a quantity passes off so rapidly from 

 the body of an insect is because it does not become latent, since the 

 circulating fluid, unlike what takes place in the higher animals, is 

 neither completely venous nor completely arterial, but of a character 

 intermediate between both. 



Twenty-one tables are annexed exhibitingtherecords of theexperi- 

 ments referred to in the paper on the respiration, temperature, and 

 circulation of insects. 



" Observations on the Dry-rot of Ships, and an effectual method 

 to prevent it pointed out." By James Mease, M.D. Communi- 

 cated by Charles Konig, Esq., For. Sec. R.S. 



The method recommended by the author for preventing the oc- 

 currence of the dry-rot in ships is to impregnate the timbers and 

 planks with common salt, as is practised by the ship-builders in 

 Philadelphia. For this purpose all the spaces between the timbers 

 and the outside and inside planks are to be filled with Spanish or 

 Portugal salt, driven down as the filling proceeds. The salt is found 

 to penetrate thoroughly, and completely to saturate the wood, com- 

 bining with its native sap and preventing fermentation and the con- 

 sequent evolution of foul air. The principal inconvenience attend- 

 ing this method is the dampness of the ships ; an evil for which the 

 author suggests various remedies. 



" Experimental Researches on the conducting powers of wires for 

 Electricity ; and on the heat developed in metallic and liquid con- 

 ductors." By the Rev. William Ritchie, L.L.D., Professor of Na- 

 tural Philosophy in the Royal Institution of Great Britain, and of 

 Natural Philosophy and Astronomy in University College, London. 



In a former communication, published in the Philosophical Trans- 

 actions for 1833, the author endeavoured to show that the quantity 

 of voltaic electricity conducted, or the force of the current, was a 

 function of a greater number of variables than had been previously 



