244 



METHODS OF CALCULATION 



in order to obtain the total necessary ampere-turns OQ". Fig. 4 

 shows how the diagrams of E.M.F.'s and of ampere-turns may be 

 united upon a single sheet. 



The preceding reasoning may be summed up in the following 

 simple equations, employing ordinary language: 



The fall of magnetic potential in the armature and air gap is a 

 function of the flux utilized in the armature a +the armature stray 

 fliix/2. 



The magnetic difference of potential between the pole pieces=the 

 fall of magnetic potential in the armature and air-gap + the reactive 

 counter ampere-turns of the armature. 



The magnetic stray field between the magnets /i+J/i = a function 

 of the difference of potential of the pole pieces. 



The total stray magnetic fluxes = the fluxes /i+J/i+the stray 



The total flux in the field magnet = the useful flux + the flux of 

 the total stray field =^+/i [i +^' ^^l +/2- 





The total ampere-turns of the field magnet = the difference of 

 magnetic potential between the pole pieces-!- the total drop of potential 

 in the field magnet corresponding to the total flux=the fall of potential 



