MORSE AND SHUDDEMAGEN. — AN ALUMINIUM ANODE. 



373 



are clamped to the side rods and the times are calculated from the 

 velocities of the falling weight as it meets the switches. The maximum 

 time of charge, discharge, or insulation which can be obtained with this 

 apparatus is about 0.6 seconds. Longer times than this are measured 

 with a stop watch. The minimum time is limited only by the delicacy 

 of the contacts used, as they must always be made strong enough to 

 withstand the heavy blow of the falling weight. The minimum time in 



100 200 300 400 500 600 



VOLTAGE 



Figure 2. 



A. Capacity of an aluminium condenser at various formation voltages. 



B. Quantity = C X V from curve A. 



C. Energy = C X V 2 from curve A. 



Long charge. Long discharge. Insulation time, 0.002 seconds. 



most of our experiments is of the order of 0.001 seconds, and this can 

 be measured with considerable accuracy. Three ballistic galvanometers 

 were used in this work. Where a long series of measurements was to 

 be made, involving a large range of capacities, the first readings at 

 higher voltages were made on the least sensitive galvanometer, and as 

 the voltage was decreased until the throw of this galvanometer was no 

 longer sufficient to give the necessary accuracy, connections were thrown 

 over to the second and more sensitive galvanometer and readings con- 

 tinued with its aid. The periods of the galvanometers were 1, 4, and 9 

 seconds respectively. It has already been mentioned that the discharge 



