62 Proceedings of the Royal Society of Victoria. 



K=Const., 1 = ^— ^, c = l+;;P.,. (IV.) 

 where n is a small fraction. 



Again we have the full load output 



P,= i7fwAF (q.p.) 

 for a non-inductive load on which the transformer would be rated, 

 but 



and 



^=W7=4//3'V|S^8- 



hence 



W -^' 



pSinS 

 where D is a constant. 



Substituting in equation I. for b and ^, their values determined 

 from II. and V., we get 



where M is a constant. 



Now I find for the same sample of iron that 



I 



is very nearly constant when w is constant over the range of flux 

 densities, or of Is, commonly used in transformers, and that it 

 increases slightly as iv diminishes. 

 Taking it as constant, we get 



Hence if r for a transformer of a given type be known, the 

 equation 



T" 



— ^= Const., 



will enable us to obtain fairly approximate values of t for other 

 transformers of the same type that differ in capacity and 

 periodicity. 



It is worth noting that equation V. above shows that, for equal 

 heating or equal iron and copper losses per unit volume, the out- 



