1898.] on SDme^Ncw Studies in CatJwde and Bontyen Badkitlorts. GOL 



and the whole of its energy converted into heat in the atom itself, 

 we have according to the formula 



T = 



in which 2 J 8 ' 



T = the rise in lemperatdre in degrees centigrade ; 



V = the velocity in centimetres per second ; 



J = joules equivalent ; 



S = the specific heat of nitrogen, we have the result that the rise 

 in temperature is no Jess than the stupendous figure of a2)proximately 

 50,000,000,000 degrees centigrade. 



This is upon the probably erroneous assumption that the specific 

 heat rem.ains constant; but allowing for this, and even allowing for 

 the mei-est fraction of the energy being converted into heat in the 

 atom itself, there is obviously an ample margin to admit of a tem- 

 perature being actually obtained enormously transcendinoj the electiic 

 arc or anything of which man has any knowledge. Perhaps it may 

 be objected that it is only when we come to deal with aggregations of 

 atoms that we can speak of heat, and that a hot atom is a physical 

 absurdity, ^f, however, we look upon heat as a rhythmic dance of 

 the atoms, perhaps we may also contemplate the possibility of a single 

 atom executing a pas seul, and giving })ulpes to the ether at each of 

 its movements. In any case this difficulty disappears if we imagine 

 the cathode ray particles each to consist of an nggreg-ition of atoms. 



The fact that substances of high atomic weight form the most 

 efficient anti-cathodes, lends force to the suggestion that the Eontgen 

 rays are produced in some way by the sudden removal of velocity 

 from the atoms that form the cathode rays, owing to the collision of 

 these latter with the comparatively stitionury atoms of wliich the 

 anti-cathode is composed ; while the efiect observed with the pin-hole 

 photographs of the anti-cathode, in which, as has been seen, the 

 cathode rays that strike the anti-cathode most nornjally are the most 

 eifective in producing lioiitgen rays, is ulso in accordance with this 

 view. At the same time, the fact that in Eontgen ray photi graphs 

 of Birkeland's cathode ray spectrum it is always the least deflected 

 ray that produced tlie greatest photographic eiiVcfc, goes to show that 

 the higher the velocity of the cathode ray atoms the more efiective 

 these latter are in generating the Itontgen rays. 



In conclusion, I must express my great indebtedness to the very 

 able assistance of Mr. J. C. M. Stanton and Mr. H. L. Tyson Wolfi". 

 The latter has blown nearly all the tubes that 1 have been able to 

 show this evening, while the aid of the former has also been of great 

 value in a class of experimenting that require s much time and labour. 

 More than two years have now elapsed since the date of Eontgen's 

 discovery, and nearly twenty years since the commencement of the 

 researches of Crookes. Here, as always, we find that " Art is long, 

 opportunity fleeting, experiment uncertain, judgment difiicult." 

 Thus wrote the Greek Hippocrates some twenty-three centuries ago, 

 and time has not impaired the truth of the ancient a])horisni. 



[A. A. 0. S.J 



