[ 390 ] 

 LV. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 325.] 



February 2, 1865. — Major General Sabine President, in the Chair. 



HHHE following communications were read : — 

 JL " Researches on Solar Physics. — Second Series. On the Beha- 

 viour of Sun-spots with regard to Increase and Diminution." By 

 WarrenDe la Rue, Ph.D., F.R.S., Balfour Stewart, A.M., F.R.S., 

 and Benjamin Loewy, Esq. 



One of the authors of this paper having been led, from a preli- 

 minary investigation, to suspect that the behaviour of sun-spots with 

 respect to increase and diminution refers to some extraneous influ- 

 ence, they resolved to investigate the behaviour in this respect of the 

 spots observed by Carrington, in addition to the Kew photograms up 

 to the present date. 



The authors have thus examined materials embracing a period of 

 ten years, and in this paper state the result. 



The nature of their examination is thus described : — 



If we imagine great circles of ecliptical longitude to be drawn from 

 the sun's centre, every point of the sun's surface as it moves round 

 by rotation will of course pass successively through each of those 

 great circles, and every one of the planets will do the same as they 

 move round by their own proper motions. 



And if we imagine the plane of the paper to denote the plane 

 of the ecliptic, and project upon this plane each body of our system, 

 we shall have a scheme similar to the above, in which ADB, the inner 

 circle, may represent the sun himself, the next circle, let us say the 

 orbit of Venus, the next that of our earth, while the outer may denote 

 the orbit of Jupiter. To an observer looking down upon our system 

 from the north, all motions will be in the direction of the arrow-heads, 

 that is to say, in a direction contrary to that of the hands of a watch, 

 or left-handed, while ecliptical circles of longitude will be represented 



