38 



[March 6, 



Crookes tube, e. g., the rapid rotation of the radiometer when exposed 

 to it. This current or stream, of whatever it may be composed, is 

 striking with great intensity and velocity more than four hundred 

 million times per second against a thin film of glass which is not in a 

 normal condition of equal pressure on both sides — on one side is a 

 vacuum more or less perfect, on the other the w^hole pressure of the 

 atmosphere. Such rapid blows cannot do otherwise than place the 

 glass in an electrically excited condition — precisely like that of the plate 

 of an ordinary electrical machine. As the exciting cause in this case is a 

 current of negatively electrified molecules of air, the inner surface would 

 be negative, and the outer intensely positive, and this would induce cor- 

 responding conditions in all neighboring bodies. The current might be 

 very small, but of very high potentialitj^ ; hence would penetrate 

 deeply these surrounding bodies, but would also produce in them all 

 the phenomena of induction. To this excited condition of the glass 

 film of the Crookes tube we may refer the phenomena of phosphores- 

 cence, fluorescence and heating, which ensue by the transmutation of 

 forces — ^just as when a stone is thrown into a pond waves of various 

 size and frequency will be seen to be propagated and interfere with each 

 other. That induction is the cause of the formation of the picture is 

 rendered probable by the fact that the reduction of the silver salt takes 

 place next to the glass of the photographic plate, and not on the free or 

 gelatin surface ; and I would suggest as worth}' of experiment whether 

 the same efl'ect would not be produced through a series of similar plates 

 and not only on the uppermost one. Prof. McFarlan, of Easton, has 

 shown beautiful results proving the radiation of the energy from the 

 cathode of the tube, which also accord with the induction lij'pothesis. 

 "With regard to the useful applications of these rays, they seem to me to 

 aftord a rational explanation of some of the benefits of the currents of 

 induced electricity on nutrition and other vital functions, which those 

 of us who have emploj-ed it in our medical practice have often observed 

 Avithout being able fully to explain, and which we can therefore use 

 more intelligently and beneficially hereafter. So also with the ettects 

 of the direct sun-rays, or sun-bath, known from ancient times. 



The plate shows the edge of the coins and other metallic bodies not 

 clearly defined, but surrounded as if with a shadow, or shading off; 

 this, when examined closely, seems to be composed of fine lines radiat- 

 ing from the coin or metal. 



I therefore believe that the phenomena in question will be found to 

 be due to an induction of statical electricity, in great measure if not 

 entirely. 



It may be well also to call attention to the fact that while sound, heat 

 and light can be reflected, refracted, transmitted or absorbed, no similar 

 phenomena have as yet been shown as to electric, galvanic or mag- 

 netic forces. 



NcAV nomination for mcnihcrsliip lo-tG Avas reaJ. 



