Page:Proceedings of the Royal Society of London Vol 60.djvu/311

Rh a little separated, thus forming apertures by which liquid could enter or leave the annular inner core.

The nature of this transformer is shown in Fig. 1.

Diagram of the Closed Circuit Transformer used in the Experiments.

The mean perimeter of this rectangular-sectioned endless solenoid was 131 cm., and the solenoid had, therefore, very nearly 3'5 turns per cm. of mean perimeter. When immersed in liquid oxygen a coil of this kind will carry a current of 50 amperes. When a current of A amperes is sent through this coil the mean magnetising force in ihe axis of this solenoid is, therefore, represented by 4'375 times the current through the wire, hence it is clear that it is possible to produce in the interior of this solenoid a mean magnetising force of over 200 C.G.S. units. This primary coil had then wound over it, in two sections, about 400 or 500 turns of No. 26 silk-covered copper wire to form a secondary coil. The primary and secondary coils were separated by layers of silk ribbon. The exact number of turns was not counted, and as will be seen from what follows it was not necessary