On the Direction of the Vibrations of the Luminiferous JEther. 49 



I regret that Dr. Tyndall should have spoken of my views of 

 these experimental inquiries as partial; one of the results 

 obtained should be an answer to that charge^ where I have had 

 occasion to establish a general law, that electricity, of whatever 

 tension, heats a conductor unequally. For the rest I am willing 

 to abide his decision, or the decision of those who m^y come 

 after him, in the matter of the supposed production of cold by 

 electricity, for I feel confident that the onward progress of science 

 never will establish such a law; while to M. Peltier, the origi- 

 nator of these inquiries, due honour will be done ; and it will 

 be remembered that when he was experimenting, he had not the 

 benefit of any previous researches to guide him. 



Although experiment is the only Csesar to whom appeal can 

 be made in a case of this kind, still there are advantages to be 

 derived from looking at what may be expected from other known 

 laws of heat and electricity. The admirable researches of 

 Mr. Joule, which have appeared in the pages of this Magazine, 

 show that the resistance to conduction and the heat developed by 

 an electrical current are always in direct proportion ; from which 

 it may be inferred, that where there was no resistance there would 

 be no heat; and again, if there was absorption of heat, the converse 

 of resistance should be looked for; what kind of force in a 

 thermo-electrical joint this can be was the difiiculty I have felt 

 in reflecting on the supposed fact of the absorption of heat by 

 electricity circulating in conductors which resist its passage in 

 a greater or less degree. 



XI. On the Direction of the Vibrations of the Luminiferous jEther 

 in Plane-polarized Light. By W. Haidinger*. 



Physical proof of the proposition that the vibrations of the lumini- 

 ferous (Ether in plane-polarized light are perpendicular to the 

 plane of polarization, 



1. r^BSERVATION. — Let a dichromatic uniaxal crystal be 

 regarded in a 



direction perpendicular . -A- 



to the principal axis. j 



The line AA' in the 



adjacent figure is the axis 



of the crystal, BB' the 



direction along which the 



eye observes the crystal, C :A'^ ] C* 



CC'the transverse direc- 

 tion perpendicular to the b' 



two others. 



Let the crystal be re- 

 garded in ordinary light, 



and let the phsenomena 



a! 



'^ From PoggendorfF's ^/m«Zew, vol. Ixxxvi. p. 131. 

 Phil. Mag. S. 4. Vol. 5. No. 29. Jan. 1853. E 



