Page:Proceedings of the Royal Society of London Vol 60.djvu/197

180 bottom of th e tube, a very b rig h t cone of blue luminescence w ith a still b rig h ter w hitish blue core, made its appearance. W hen under these conditions the tube was slightly moved sideways, the bright spot a t the apex of the cone, and the cone itself moved, the spot and apex always m aintaining a position exactly over the centre of the m agnet pole. A t the same tim e th e m inor blue luminescence proceeding from th e anode term inal, due probably to the “ make ” current of the RuhmkorfE coil, was bent downwards towards the m agnet as shown, and deflected sideways one way or another according to the polarity of the m agnet, which polarity, however, did not affect in any way the vertical cathode stream. The internal resistance ot th e tube, as m easured by an alternative spark gap on the RuhmkorfE coil, was also found to be very greatly diminished while th e m agnet was excited. W ith th e m agnet not excited, the altern ative spark would leap from 1^ to li| inches, while, when the m agnet was excited, the gap had to be reduced to about inch before th e sparks would pass. As soon as the current from the m agnet was cut off, the appearance of the tube im mediately reverted to w hat is shown in fig. 1, and its internal resistance increased to what it had been before.