﻿492 Mr. J. B. Henderson cm the Effects of Magnetic 



about which temperature the cement between the mica plates 

 melted ; but in the small spiral this cement was changed for 



Fig. 3. 



shellac, and it could therefore be heated to 80° C. On this 

 account, therefore, as also on account of the higher fields in 

 which it could be placed, the results obtained from the small 

 spiral are more interesting and important. 

 In the case of the water-bath for the small spiral (see fig. 4) 



Fig. 4. 



the pole-pieces themselves were made to form part of the 

 vessel. The two brass rings to which the poles w r ere soldered 

 were connected outside by a cylindrical brass tube of large 



