184 Proceedings of the Royal Society of Edinburgh. 



1 . As far as has been observed, the vibrations never take place be- 

 tween substances of the same nature. 2. Both substances must be 

 metallic. 3. The vibrations take place with an intensity propor- 

 tional, within certain limits, to the difference of the conducting 

 powers of the metals for heat (or eleclricily*) the metal having the 

 least conducting power being necessarily the coldest. 4. The time 

 of contact of two points of the metals (between which the oscillations 

 take place) must be longer than that of the intermediate portions. 

 5. The impulse is received by a distinct and separate process at 

 each contact of the bar with the block, and in no case is the connec- 

 tion of these points in any way essential. 6. The intensity of vibra- 

 tion is (under certain exceptions), proportional to the difference of 

 temperature of the two metals. 



From these data, the author first endeavours to show, that the 

 hypothesis of expansion is untenable, by tracing closely the process 

 of communication of heat, and proving that it must lead to several 

 conclusions totally at variance with experiment, and particularly 

 that as far as conducting power for heat is concerned, both the hot 

 and the cold metal should possess it in the highest degree. The 

 author is led by the striking analogy of the powerful repulsive action 

 of electricity in passing from a good to a bad conductor, to infer a 

 similar property in heat, which, without entering into any specu- 

 lations as to the nature of those principles, appear to have a repul- 

 sive character in common indicated by a tendency to diffusion and 

 equilibrium. He conceives, that while some very delicate experi- 

 ments in France have given indications of the actual force exerted 

 by heat equally diffused through two adjoining masses, that the 

 energy in this case is produced by the accumulated repulsive power 

 in the last particles of the good conductor, the current (without 

 meaning any thing hypothetical by the term) being suddenly cut 

 short by the resistance opposed by the inferior conductor to its pas- 

 sage. The destructive energy of electricity indicative of its repulsive 

 force, is never exerted in a state of equilibrium, but by the accumu- 

 lation of separate repulsive energies which take place in the transi- 

 tion from a good to a bad conductor, or during its passage through 

 the jatter. 



2. On the Equations of Loci traced upon the surface of the 



Sphere, as expressed by spherical co-ordinates. By T. 



S. Davies, Esq. F. R. S. E. 



This paper is intended as a necessary supplement to the paper 



bearing the same title already printed in the Society's Transactions, 



• See the abstract of a former paper on. the identity of those arrangements. 



