Phenomena of the Approach and Recession of Bodies. 69 



Art. XVI. — The Sciopticon. 

 By W. M. Cooke. 



[Eead 17th May, 1875.] 



Art. XVII. — Notes concerning the Phenomena of the 

 Approach and Recession of Bodies under the Influence 

 of Radient Energy. 



By Alfred Mica Smith, B.Sc. 



[Read 14th June, 1875.] 



[ABSTRACT.] 



The subject of this paper, the author said, is far from 

 being a new one, having engaged the attention of several 



O ' o © o 



physicists of repute during the last eighty years. It has 

 recently been brought very prominently before the scientific 

 public by the elaborate experiments of Mr. William 

 Crookes, F.R.S., who has attacked the question of the 

 causation of the motions concerned with persevering 

 industry, and with the aid of refined apparatus of a 

 character wholly beyond the reach of the earlier investi- 

 gators. Mr. Crookes' results and the expression of his 

 views have led to the performance of experiments and the 

 expression of theoretical views, on the part of Professor 

 Osborne Reynolds, of The Owens College, Manchester ; 

 Professor Reynolds' views and deductions appearing to differ 

 widely from those of Mr. Crookes. The question of the 

 causation of these remarkable motions remains therefore yet 

 an open one. The quantities dealt with are small in 

 amount ; the experimental means are delicate and susceptible 

 of influence from very slight disturbing causes ; the whole 

 question is subtle, bordering closely on the confines of the 

 unknown in molecular physics. But the subject, although a 

 difficult one, is also confessedly one of high moment and 

 great interest, and as after many experiments the author 

 had arrived at certain results, some of which appeared to be 

 not wholly devoid of interest, he ventured to select a few 

 therefrom to place before the Society, in the hope that they 

 might contribute some small amount of collateral testimony 

 ±o be added to that already adduced. It was further added, 



