Origin of Cometary Bodies and Saturn s Rings. 741 



The same cycle is represented in the figure both on the Yx 

 and L# diagrams, A, B, C, and D corresponding on the one 



x, 











diagram to A', B', C, and D' on the other. The work done 

 in the cycle must be zero. The two parallelograms are tra- 

 versed in opposite directions; hence their areas must be 

 equal. 



ABCD 



and 



A'B CD' 

 Therefore, on equating, 



dF%~dL, 

 <*l|£ dF. 



There are no measurements available for testing the relation. 

 E. G. Coker (Edin. Trans, xl. p. 263, 1901-02) has tried both 

 the effect of tension on torsion and torsion on tension, but the 

 results are hardly greater than the error of observation. 



^ it' 



In any case ™ would be extremely difficult to determine 

 experimentally. 



LXXIII. On the Origin of Cometary Bodies and Saturn s 



Rings. By Henry Wilde, D.Sc, B.C.L., F.R.S.* 



[Plates XIV. & XV.] 



AS the first Halley Lecture which I delivered before the 

 University of Oxford in May lastf contained some 

 matters new to astronomical science, it has appeared to me 

 that an abridgment of the lecture, with some additions 



* Communicated by the Author. From the Manchester Memoirs, 

 vol. lv. 1910, no 1. 



t Clarendon Press. Frowde. 1910. 



