1892.J 



Dynamo-Electric Machinery. 



55 



68*3 sq. cm.* Hence, an ordinate of 1 cm. represents an induction of 

 1024 lines per square centimeter. The difference between ordinates at 

 50° and 140° is 2*5 ; hence the difference of induction is actually 2560. 

 Theoretically, we have k — \ irm = 104 C = 9*4. Therefore, 2/cmC 

 = 3072, and this is the line integral of magnetising force round 

 curve. 



Let A be the induction at 50° and A + £ at 140° : these also are the 

 magnetising forces. Hence, (A + 1*4— A 1*4 = 2/cmC; S = 2200 

 as against 2560 actually observed. 



* In calculating this area, the allowance for fringe at ends of armature is taken 

 less than before, because the form of opposing faces differs. 



