304 British Association for the Advancement of Science. 



On Electrical Attraction. By W. Snow Harris. 



The object of this paper was to examine the operation of attrac- 

 tion in electricity, and the laws and differences between the force of 

 attraction actually exerted between two bodies, and the force excited 

 in a neutral uninsulated body, by the influence of a charged body 

 acting upon it at a distance. He endeavoured to show that the 

 former force varied in an inverse ratio of the distance simply ; that 

 the law of the inverse square of the distance, which is the general 

 law for the former force, does not obtain at all distances between 

 bodies, except one of them be uninsulated and neutral ; and that in all 

 cases of attraction there are two previous forces to be considered, 

 1st, the force directly induced in the neutral body ; 2nd, the effect 

 of this induced force upon the charged body ; which last he calls 

 the reflected force, and attempted to prove that the whole attrac- 

 tive force between these bodies varies with these forces conjointly, 

 so that if one of them becomes fixed it varies with the other. He 

 exhibited and described several new experiments in electricity re- 

 lating to electrical induction and attraction, and expressed his opi- 

 nion that the whole attractive force was dependent on the action 

 excited in the neutral bodies reflected on the charged body. This 

 principle, with but little modification, he further applied to any case 

 of electrical attraction whatever. 



On the Application of the Proof Plane and Torsion Balance to in- 

 quiries in Electricity. By W. Snow Harris. 



Mr. Harris conceives that an insulated plate of metal of small 

 thickness may take up unequal quantities of electricity from a body 

 and yet the distribution be uniform. The experiments in illustration 

 of this were fully discussed. He alluded to several laws of elec- 

 trical intensity attendant on the disposition of electricity on surfaces 

 and plates varying in extension and in length, but of the same area, 

 and endeavoured to show that contrary to the ordinary view of 

 electrical distribution, electricity existed on both surfaces of a hol- 

 low sphere, as well as on both surfaces of a plate of the same area. 

 He considers every case of attraction in electricity to resolve itself 

 into the case of charging a coated non-conducting body, and that 

 the phaenomena always correspond to those observed in the latter. 



On the Aurora Borealis. By Sir John Ross. 



Having observed in his first arctic expedition that the aurora 

 sometimes appeared between the two ships, and also between the 

 ships and the icebergs, and found in his subsequent experience, 

 both in Scotland and during the second arctic voyage, proofs satis- 

 factory to his own mind that the aurora takes place within the 

 cloudy regions of the earth's atmosphere, Sir John Ross states 

 the following hypothesis on the subject, viz. " The aurora is en- 



