﻿On Gauss's Conception of Electrodynamic Phenomena. 445 



haps in this construction it would be necessary to employ a tube 

 of tempered steel, but probably one of brass or copper might 

 suffice. 



I will only further add that the moveable connector which I 

 have described has been found to work most satisfactorily. It 

 can be mounted or dismounted in an instant ; and if at any time 

 it be desirable to revert to the use of a vulcanite connector, all 

 that is needed is to pull the vulcanite over the cones D on to the 

 tubes A and B. 



In conclusion I cannot omit the opportunity now afforded me 

 of warmly recommending, with or without the new connector, 

 Blanches most elegant and useful air-pump. Owing to the very 

 great rapidity with which, by its use, a vacuum can be obtained, 

 it is particularly well adapted for lecture-experiments. The 

 pump-cylinder and nearly all the apparatus being made of cast 

 iron, is not liable to suffer corrosion from oil, and will therefore, 

 I have no doubt, last much longer than a brass air-pump. I 

 have found a glass case very effectual in preventing external 

 rusting ; and the instrument is so beautifully finished as well 

 to deserve such protection. M. Bianchi has adopted in his 

 air-pumps Babinet's ingenious arrangement for double exhaus- 

 tion. By turning a stopcock, one end of the barrel of the pump 

 is made to exhaust the other ; and thus a very perfect vacuum, 

 as is well known, can be obtained. 



LXII. Upon the new Conception of Electrodynamic Phenomena 

 suggested by Gauss. By R. Clausius*. 



IN a letter written by Gauss in 1845 to "W. Weber, the brief 

 remark occurs that he considered the corner stone of elec- 

 trodynamics to be the deduction of the accessory forces (which are 

 superadded to the reciprocal action of electrical particles at rest) 

 not from an instantaneous action, but (as is the case with light) 

 from one requiring time for its propagation. Based upon this 

 remark, three very interesting papers, by Biemann, C. Neumann, 

 and Betti, have lately appeared. All three authors arrive by dif- 

 ferent ways at the result that the forces which two currents 

 exert upon each other are explicable on the assumption that a 

 certain time is necessary for the propagation of electrical actions. 

 I have read these researches with the greatest interest, but 

 must confess that I am not satisfied with them ; and I think 

 that both the well-deserved reputation which these authors possess 

 in the scientific world, and the importance of the subject, amply 

 justify me in stating my objections. The fact that three distin- 



* Translated from a separate impression, communicated by the Author, 

 from Poggendorff' s Annalen for December 1868. 



