120 Transactions. — Miscellaneous. 



tected from the bombardment, was apparent behind it. The 

 material character of the electrical discharge, and the actual 

 transport of matter by electricity, were thus demonstrated by 

 Varley, but his experiments and their results remained for 

 many years quite unnoticed. 



Eventually, however, the matter was taken up by Crookes. 

 After studying the mechanical work of light rendered evident 

 by the radiometer, he devoted his attention to the phenomena 

 indicated by Varley, and, utilising the enormous progress in 

 mechanical science which had taken place since the latter had 

 made his experiments, he obtained such an exhaustion of the 

 Geissler tube as to leave in it only a few millionth parts of the 

 air which it had originally contained. With this more perfect 

 instrument of research he soon accumulated a vast array of 

 important facts. He demonstrated that the electrical excita- 

 tion of the negative terminal of the tube produced a molecular 

 disturbance which affected the surface of the terminal, and 

 that on this disturbance being communicated to the rarified 

 gas in the tube a real torrent of material particles, wdiich he 

 treated as molecules of the residuary gas within the tube, 

 rebounded from the surface of the negative pole in a direction 

 normal to that surface. He also determined the velocity 

 with which these molecules moved, which, of course, varied 

 with the intensity of the current, and found that they did so 

 at a speed varying from one to two miles in a second. But 

 the most interesting observation which he made was that the 

 torrent was composed of particles so material in character 

 that a magnet exercised a powerful effect upon them, curving 

 their trajectories in the same manner as gravitation acts upon 

 a bullet fired from a gun. He also noted that the phos- 

 phorescent glow of the tube did not emanate from the particles 

 themselves, but was produced by their impact upon the 

 surface of the glass, to which they evidently imparted suffi- 

 cient energy not only to render it luminous, but also to raise 

 its temperature. From these effects he justly concluded that 

 the particles thrown off from the negative pole and striking 

 the glass were truly material. These experiments have been 

 repeated and verified by a large number of observers in the 

 first rank of electrical science, who have also come to the 

 conclusion that particles of matter are projected by electricity 

 at great speed from the negative terminal of a vacuum tube, 

 and that tliis effect, coupled with their behaviour towards the 

 magnet, and their sensitiveness to the approach of any con- 

 ductor, affords a positive demonstration tliat the component 

 particles of gas in the tube had been electrified by the dis- 

 charge. In these remarks I have advisedly used the word 

 " particle " in connection with the stream projected from the 

 negative pole of the vacuum tube. Unfortunately, confusion 



