INTRODUCTORY 9 



This last effect, which may be attributed to the cutting of the 

 magnetic lines by the electric conductors, will be considered 

 when taking up the design of dynamos. For the present it will 

 be advisable to investigate condition (1) only, and Chaps. 

 II and III will be devoted to the study of the magnetic circuit; 

 to the calculation of the excitation required to produce a given 

 magnetic flux; or, alternatively, the quantitative determination 

 of the flux when the size, shape, and position, of the exciting 

 coils are known. 



