290 



Exp. X. 



Profs. J. A. Fleming and J. Dewar. On the 



right 



f 



I 12 

 -| 12 -0 

 j 12*2 



^ 



""I The transformer lifted out of liquid oxygen 

 '0 mm. to right into cold gaseous oxygen at the same tem- 



perature. 



Current = 28 '1 amperes reversed through 

 J primary coils. 



The transformer in liquid oxygen. 



{1 e ransormer n qu oxygen. 

 I Current = 28 '1 amperes reversed through 

 " " J primary coils. 



Exp. XII. 



The above table shows the results of the observations made with 

 the small transformer alternately placed underneath the surf ace of 

 liquid oxygen, and then lifted up into the cold gaseous oxygen lying 

 above the surface of the liquid oxygen. It will be noticed that the 

 ballistic throws in each set of observations are not constant, but that 

 there is a tendency, usually, for the throw to increase if repeated, 

 whilst the transformer is still maintained in the same condition, 

 This is in all probability due to the fact that the continued passage 

 of the primary current heats the primary circuit of the balancing 

 induction, coil, and hence heats, also, by radiation, the secondary coil 

 of the balancing induction coil, and, therefore, by enlarging the area 

 of the adjusting coil, continually breaks down the inductive balance. 

 It was found necessary, therefore, to take the observations in groups 

 at equal intervals of time. First, a group of three observations was 

 taken, the transformer being in liquid oxygen, the balance being, as 

 nearly as possible, obtained. Then the transformer was lifted out of 

 the liquid oxygen, and the ballistic throws again taken, reversing the 

 same primary current ; next again immersed in liquid oxygen, and 

 finally once more taken out of the liquid oxygen. Taking the sets 



