dependent on the Motion of the Conductor. 101 



than in the foregoing experiments ; this results clearly from 

 equation (9). On this account, the experiments had to be 

 conducted with suitable precautions to prevent the polarization 

 from affecting the direction of the deflections. Before each 

 experiment the electric series had to remain a longer time 

 closed in order that the disks might be completely polarized. 

 During this time the water-cock was several times turned on 

 and off. It was only after this had been done that I could 

 reckon upon obtaining constant and regular deflections. It 

 must, besides, be remarked that the galvanic current employed 

 should not be too powerful, because the harmful effect arising 

 from the galvanic difference between the disks increases with 

 the intensity of the current. In the following experiments 

 two Daniell's elements were employed. Out of the observa- 

 tions thus conducted, it will be sufficient to give the two fol- 

 lowing series. A, B, and D have the same signification as 

 before. 



Series 3. — Here another glass tube was employed ; but the 

 distance of the disks from each other and the diameter of the 

 tube were about the same as in the first tube. The velocity of 

 the water, when the cock was turned full on, amounted to about 

 10 metres per second. In reckoning the magnitude of the 

 deflections, the mean was taken of two successive positions of 

 equilibrium with still water. 



The negative pole of the electromotor was connected with 

 the middle disk : 



A. B. D. 



608-0 611-0 2-6 



608-8 611-2 2-3 



609-0 610-2 1-2 



609-0 610-5 1-5 



609-0 611-0 2-0_ 



609 ' 9 Mean . . 1'92 



The positive pole connected with the middle disk, the rest 

 unchanged : 



* A. B. D. 



626-5 



628-8 



2-3 



626-5 



627-5 



1-7 



625-0 



628-5 



3-0 



626-0 



627-5 



1*7 



625-5 



627-2 



1-2 



626-4 



Mean . 



. 1-98 



The direction of the deflections indicated in both cases that 

 the resistance is diminished when the galvanic current and the 

 water-flow coincide in direction. 



