60 



KENNELLY-SANBORN— INFLUENCE OF 



[April 24, 



stationary gauze brushes. The electrical connections are as shown 

 in Fig. 3. The source of e.m.f. was a storage battery. The regulat- 

 ing resistance RR was so adjusted that the ratio of the p.d. between 

 pressure-wires, to the current strength, was equal to a predetermined 

 resistance. That is, the current in the test-wire was gradually in- 

 creased until the ratio of the reading of the voltmeter V to that of 

 the ammeter A, was found, by slide-rule, to give the correct resist- 

 ance sought to be maintained in the test-wire at all wind speeds. 



<Ocm 



•<r 3 Bern. 



Fig. 3. Diagram of Electrical Connections. 



As the driving speed increased, the current supplied to the wire had 

 to be increased, in order to maintain this ratio V /A. When, on the 

 contrary, the driving motor was brought to rest, the current in the 

 test-wire had to be reduced to a relatively small value, in order to 

 reproduce the ratio. 



The fork was mounted on the shaft of a 5^-HP. 115-volt direct- 

 current shunt motor, arranged to run at adjustable speeds. The 



