1892.] on Alternate Currents of High Potential and Frequency. 651 



and puslied under the molecular impact. It was observed in such 

 experiments that the carbon cup was heated at first, until a higher 

 temperature Mas reached; then most of the bombardment was 

 directed against the refractory body, and the carbon was relieved. 

 In general, when different bodies were mounted in the bulb, the 

 hardest fusible would be relieved, and would remain at a consider- 

 ably lower temperature. This was necessitated by the fact that 

 most of the energy supplied would find its way through the body 

 which was easier fused or " evaporated." 



Curiously enough it appeared in some of the experiments made, 

 that a body was fused in a bulb under the molecular impact by 

 evolution of less light than when fused by the application of heat in 

 ordinary ways. This may be ascribed to a loosening of the structure 

 of the body under the violent impacts aiid changing stresses. 



Some experiences seem to indicate that under certain conditions 

 a body, conducting or nonconducting, may, when bombarded, emit 

 light, which to all appearance is due to phosphorescence, but may in 

 reality be caused by the incandescence of an infinitesimal layer, the 

 mean temperature of the body being comparatively small. Such 

 might be the case if each single rhythmical impact were capable of 

 instantaneously exciting the retina, and the rhythm just high enough 

 to cause a continuous impression in the eye. According to this view, 

 a coil operated by disruptive discharge would be eminently adapted 

 to produce such a result, and it is found in experience that its power 

 of exciting phosphorescence is extraordinarily great. It is capable 

 of exciting phosphorescence at comparatively low degrees of exhaus- 

 tion, and also projects shadows at pressures far greater than those 

 at which the mean free path is comparable to the dimensions of the 

 vessel. The latter observation is of some importance, inasmuch as 

 it may modify the generally accepted views in regard to the " radiant 

 state " phenomena. 



A thought, which early and naturally suggested itself, was to 

 utilise the great inductive effects of high frequency currents to pro- 

 duce light in a sealed glass vessel without the use of leading-iu 

 wires. Accordingly, many bulbs were constructed in which the 

 energy necessary to maintain a button or filament at high incan- 

 descence, was supplied through the glass either by electrostatic or 

 electrodynamic induction. It was likewise easy to regulate the 

 intensity of the light emitted by means of an externally applied 

 condenser coating connected to an insulated plate, or simply by 

 means of a plate attached to the bulb which at the same time per- 

 formed the function of a shade. 



A subject of experiment, which has been exhaustively treated by 

 Prof. J. J. Thomson, has been followed up indepondently by the 

 author from the beginning of this study, namely, to excite by electro- 

 dynamic induction a luminous band in a closed tube or bulb. In 

 observing the behaviour of gases, and the luminous phenomena 

 obtained, the importance of the electrostatic effects was noted and it 



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