344 Mr. E. H. M. Bosanquet on Electromagnets. 



series. This is fitted specially in the region from 38 =7000 

 upwards, which includes the dynamo range. 



- = 210 + 150 sin + 26 sin 30 + 8 sin 50 + 2 sin 70, 

 P 

 where 0=-O12{B-4OO}°. 



III. Representation by means of my rule that 



p = shape-constant + -> 



with rough approximate value of /ul. The shape-constant 

 for unit length '00252 in this case is derived from my in- 

 vestigation cited above. General values for this will be the 

 subject of further investigation. 



I 1 



-= =r> 



9 -00252+ i 

 where p = 300 + 2000 sin 0, 



This fits fairly up to % =16,000, but fails above. It is a 

 useful formula for an approximation to the general outline. 



IV. Representation by means of the tangent law. 



Magnetizing force = CQnductivity = * tan m 

 Fitting to the 15,000 entry, 



& = 1-28031; 

 then 



The differences are only entered when there is some approxi- 

 mation to the truth. 



V. Frolich's law. 



Conductivity = - = ~ . =*(^« -»)• 



J p magnetizing force v 7 



This is shown by the straight line on the figures. It is 

 unnecessary to exhibit the calculation of the numbers. The 

 correspondence with the truth is about the same as in the 

 tangent law ; but the error increases more rapidly, and ulti- 

 mately becomes much larger, as the magnetism diminishes. 



