114 



Trans. Acad. Sci. of St. Louis. 



This is the equation of the characteristic of the dynamo. 

 A curve drawn on fig. 1 from eq. (8) will give a curve co- 

 inciding with the characteristic of the machine which would 

 be drawn from the data throughout all working conditions 

 and would depart from it only for extremely low currents. 



In the preceding it has been shown that in this particular 

 case the characteristic equation of the machine determines the 

 characteristic of the machine at constant speed. 



This has been done for many machines for varying condi- 

 tions such as 



R = a constant, 



n = a constant, 



i = a constant, etc. 



and the experimental results gotten very accurately coincided 

 with the results expected from the characteristic equation — 

 eq. (4). See II. 



Fig. 4 

 Series Dynamo Cli-aracteristic. Speed Equals 1400 rev.pr. min. 



The following four pages will be devoted to a discussion of 

 the characteristic equation. The results obtained can be com- 

 pared with those gotten from any available machine. 



