A. M. Mayer on measuring Electrical Conductivities. 318 
They were reversed on each other, clamped together and had 
their terminals dipping in A and <A’ so that the two induced 
currents would tend to traverse the galvanometer coil in oppo- 
site directions. 
e mean of three experiments shows that when the spirals 
are slid off there is a deflection of 2°43 div. in favor of spiral A. 
But, on making spiral B the back spiral, the needle moved 3-9 
div. in its favor: thus showing that spiral B offers less resistance 
inductive action. But although the current in one spiral during 
the rise to its maximum causes an induced current in the other 
spiral in the same direction as that induced in it by the magnet, 
yet, as the current decreases as quickly to 0 after it has reache 
its Maximum, it follows that a current in the opposite direction 
to that induced by the magnet in the other spiral will now 
quickly follow it, and as these currents, +, and — are equal, 
there will be no increased outside effect arising from their inter- 
action ; and many experiments showed that whether a copper 
dise was placed between the spirals or an equally thick dise of 
paper, the action at the galvanometer was the same. 
-he following experiments on this subject = ei to confirm 
the above view. The two spirals were placed on the magnet, 
but only the front one was connected with the galvanometer, 
while the terminals of the back spiral were separated so that no 
Am. Jour. Sct —SEconn Serigs, Vor. L, No. 150.—Nov., 1870. 
20 
