1865.] De la Rue, Stewart, and Loewy on Solar Physics. 59 



II. "Researches on Solar Physics. Second Series. On the Behaviour 

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

 WARREN DE LA RUE, Ph.D., F.R.S., President of the Royal 

 Astronomical Society, BALFOUR STEWART, A.M., E.R.S., 

 Superintendent of the Kew Observatory, and BENJAMIN LOEWY, 

 Esq. Received January 10, 1865. 



(Abstract.) 



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

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

 increase and diminution refers to some extraneous influence, they resolved 

 to investigate the behaviour in this respect of the spots observed by Car- 

 rington, 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 repre- 

 sent 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 r.u 

 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 



