Page:Proceedings of the Royal Society of London Vol 60.djvu/316

290 Exp. X. Exp. X I.

I 12 *0 mm. to right \ 1 2 ’0 „ I 12*2 „

1 The transformer lifted out of liquid oxygen j into cold gaseous oxygen at the same temperature. Current = 28 T amperes reversed through primary coils. J 1 *2 mm. to lefc [ 1*3 „ The transformer in liquid oxygen. Current = 28 *1 amperes reversed through primary coils. Exp. XII. The transformer in liquid oxygen. The transformer lifted out of liquid oxygen into cold gaseous oxygen at same temperature. Current reversed Ballistic throw in millimetre s. Current reversed Ballistic throw in millimetres. in primary coils, Deflection to the in primary coils, Deflection to the in amperes. right. in amperes. right. 58-8 10-5 _ __ ____ — 50-2 47 *0 50 -2 15 0 — — ____ — 50-8 48-5 50-2 17-0 — — — — 50-0 49 -0

The above table shows the results of the observations made with the small transformer alternately placed underneath the surface 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