Mathematics and General Physics. 361 



Melloni, or the law of the inverse square of the distance, but 

 that his views were perfectly consistent with facts, and enabled 

 him beforehand to estimate the degree of the attractive focus 

 acting on substances of all shapes, at all distances, by conduced 

 and induced electric action. Professor Stevelly made some re- 

 marks to reconcile theory with experiment. 



11. Mr J. S. Russel gave a short account of his experimental 

 researches into the laws of the motions of floating bodies. lie 

 detailed experiments on two canals in Scotland. He shewed that 

 small models are not applicable for exhibiting the resistance of 

 large vessels, the distinction between the conditions of a floating 

 and an immersed body, with the differences from any theory, 

 and that resistance diminished with great velocities. He exhi- 

 bited a table of results, and deduced from it that the difference 

 in different canals, according to size and depth, is dependent on 

 the velocity of the wave raised. A member stated that the re- 

 sults are confirmed on two canals in Ireland, but gave a some- 

 what different explanation. Another member confirmed the 

 results. 



Wednesday, 12th August. — 12. Mr Pritchard exhibited some 

 experiments on polarization this morning before the meeting; 

 they consisted chiefly of improvements in the mode of exhibi- 

 tion. The most singular fact shewn was, the formation of a 

 certain white elliptic ring, by light passing through calcareous 

 spar. 



13. Mr Snow Harris, on the use of the proof, plain, and torsion 

 balance of Coulomb and others. He detected considerable dif- 

 ferences in the distribution of electricity in different parts of bo- 

 dies, and obtained results apparently at variance with Poisson's 

 theory. He compared various theories, and exhibited experi- 

 ments in support of his views. Mr Whewell made some re- 

 marks on the experiments of Mr Harris, and on the utility of 

 theories to assign causes. He differed from Mr Harris as to 

 the inferences from the experiments, and shewed, that many of 

 the supposed exceptions are really quite accordant with the ma- 

 thematical theory. 



14. Captain Sabine gave an account of Hansteei^s researches 

 on terrestrial magnetism, who had collected observations on the 



