186 Dr. E. H. Kennard 



on 



flux through the Faraday disk was found with a ballistic 

 galvanometer to be 0*1197 o£ that through the central section 

 of the outer cylinder, so that in the main experiment the 

 E.M.F. in the galvanometer circuit was 0*119 7 V . Hence,, 

 by proportion, the ratio of the deflexions due to induction 

 should be 



20-5 -IV 6j22V 

 62-2'-1197Vo" 7-42V ~ U ^ J " 



§ 6. The Electromagnetic Induction Effect. 



The final results on the rotation of the solenoid alone and 

 of solenoid and condenser locked together are shown in the 

 annexed table. Columns S and I give the direction of rotation 

 and the initial direction of current respectively, E and Gr 

 are the electrometer and galvanometer deflexions, and B, is 

 their ratio. " Rev. av." denotes the average effect reversing' 

 with current and direction of rotation. Four sets of readings 

 were rejected for very obvious good reason, and at onc« 

 replaced • and perhaps as many more sets were not completed 

 because of the occurrence of an obvious large disturbance. 

 To illustrate the character of the separate readings: the 

 three electrometer deflexions for the first line in the table 

 were +8*5, +4*8, +3*7; for the second, 4-22*4, +13'8> 

 + 1-8; for the fifth, +5*1, -39*1, +3*3; for the sixth, 

 -12-6, -|- 29-9, -21-5. 



S. I. . E. G. R. 



Sol — + + '4 mm. + '5 mm. 



- - + -6 - -3 



+ - - 1-1 - -6 



+ + +3-5 + -2 



Eev. av. + 1-2 



Both... + + +14-4 +60-7 '237 



- + -15-6 -65-7 -237 



_ _ _|_i6-4 +69-4 -236 



_|_ _ _l8-0 -69-8 -258 



Av. -242 



Final Observations. 



The first group of results confirms Barnett's conclusion 

 that the electromagnetic effect of rotating the solenoid alone 

 is nil. A similar group taken previously ranged from *8 to 

 2'7 mm., and gave a reversing effect of only +*2 mm. 



