338 



H. XAGAOKA. 



of circular .shape was attached. This dippsd in a mercury cup placed 

 underneath, and was in connection with one of the terminals of the 

 galvanometer coil. In order to avoid any induction current that 

 might arise from the sudden motion of the twisting arm and its 

 appendages, that extremity of the axis which served to clamp the wire 

 and lead the current to the galvanometer was insulated, from the rest 

 of the axis and the graduated circle, by a piece of wood (e). 



The other end of the wire was clamped somewhat similarly on a 

 piece of thick brass plate of rectangular shape, of which the front 

 view is shown in Fig. 3. It was provided with two V shaped projec- 



Fig. 3. Fig. 4. 



ti 



p 



w 



b 



lions (b) (/>), which could slide smoothly on V grooves cut in a brass 

 stand as shown in Fig. 4. The metal plate was prevented from 

 turning over when the wire was twisted, by means of two hooks ft) 

 (c), which slid in two grooves (<:') (c) cut on the lateral sides of the 

 stand. This groove arrangement was necessary when the effect of 

 longitudinal stress was to be studied. The longitudinal stress was 

 applied by hanging a pan of weights to the end of a flexible string 

 which was fastened to the clamping plate and passed over a pulley 

 fixed to the table. The plate was connected with the other terminal 

 of the galvanometer. 



The wire to be examined was always Avell straightened and 

 carefully annealed. AVhen the wire was to be renewed, precaution was 

 taken to cut it always from the same bundle for differences of material 

 necessarily produces difference in the transient current. The wire 



