in Cells or Direct and Alternate Currents. 



343 



as to what the resulting current would be in the circuit xy. Curves 

 in fig. 5 were obtained by observing the instantaneous value of the 

 potential difference between the ends of a non-inductive resistance of 

 0'349 ohm, forming the circuit xy, fig. 4. Four small cells 



were 



FIG. 4. 

 ALTERNATOR. 



HHHHH4HHhlh 

 HHHHWHHHF 



used, each one taking the place of the group of four in the diagram ; 

 each or these consists of a thin aluminium sheet and a carbon plate, 

 the opposed surfaces in a saturated alum solution having each 

 10 square inches, separated by a distance of -/% inch. In fig. 5, 



curve I, is the current in xy, when the current from the alternate 

 current machine through the system was 3'96 amperes, as given by 

 a Siemens dynamometer. Curve II is the current in xy, when the 

 Siemens dynamometer read 10'4 amperes. The frequencies were 

 74 and 73'3, and the temperatures of the cells 25 C. and 44 C. 

 respectively in the two experiments. Graetz states that with cells 

 VOL LXIIF. 2 c 



