852 Proceedings of the British Association. 



Section A. — Mathematics and General Physics. 

 President — Rev. Dr Robinson. - 

 Vice-Presidents — Sir Thomas Brisbane ; Mr Baily. 

 Secretaries — Professor Hamilton ; Professor Wheatstone. 

 Committee — Prof. Mosely. Mr Whewell. Prof Lloyd. Dr Drummond. Dr 

 Knight. Mr Murphy. Mr G. Rennie. Prof. Stevelly. Mr Cooper. Mr 

 Wharton, Dr Lloyd. Mr Maccullach. Mr Sadleir. Mr Fox. Mr Snow 

 Harris. Prof. Powell. Dr Dalton, Lord Adare. Lord Oxmantown. Capt. 

 Sabine. Prof. Babbage. Dr Lardner. Col. Colby. Sir J. Franklin. Capt. 

 •lames Ross. 



Monday, 1st Aug. — 1. Mr Whewell read his report on the 

 State of our Knowledge respecting the application of Mathe- 

 matical and Dynamical Principles to Magnetism, Electricity, 

 Heat, &c. 



He observed that Newton's anticipation that all physical 

 forces are to be explained by some application of the principles 

 of dynamics, is verified by the subsequent progress of science, 

 and that the only legitimate theories of heat, electricity, magne- 

 tism, &c, are such as are founded on numerical results, reduced 

 to laws. This has been, in a great measure, accomplished; and, 

 therefore, mechanical reasoning is applicable. 



He then compared the two theories of electricity, noticing the 

 application of the higher analysis by Poisson, Mr Snow Harris's 

 valuable results, Barlow's Laws of Magnetism, and Bonnycas- 

 tle's Mathematical Theory, which agrees with experiment and 

 with Poisson's Theory, applied to magnetism. 



He appeared to consider that theory untenable, which sup- 

 poses the existence of one fluid only. He brought forward ex- 

 amples of the distribution of the electric fluid on the surfaces of 

 solids of different forms, which were readily accounted for, on 

 the theory which assumes the existence of two fluids. In con- 

 nexion with this subject, allusions were made to some statements 

 and experiments of Mr Harris, presented to a former meeting 

 of the Association. Mr W. shewed that similar objections were 

 made to that magnetic theory which required the admission of 

 one fluid only, but that these were not applicable to a theory 

 found t-d on the supposition of two fluids. 



Mr Harris explained, and endeavoured to shew that there is 

 no law for the diffusion of the electric fluid on surfaces of dif- 



