MM. Wolf and Fritz on Sun-spots. 75 



curve of solar spots over that of temperature. At the maximum 

 about 1856, however, this does not appear to be the case ; but when 

 the uncertainties of the data, both of the solar spots near the mini- 

 mum, and of the mean temperature also, are taken into account, 

 such discrepancies might perhaps fairly be expected, even if there 

 be a physical connexion between the two phenomena as results of 

 some common cause. If there be a sensible inequality in the mean 

 temperature with a period of about ten years, then the mean tem- 

 perature resulting from the observations in the temporary Observa- 

 tory, which were made near a maximum, will be too high. The 

 corresponding ordinates, therefore, will be depressed too much rela- 

 tively to those corresponding to observations made in the other two 

 observatories. In the curve 2, I have imperfectly corrected the mean 

 of the results for the temporary observatory on the supposition of 

 such an inequality existing. The only result of such a correction is 

 .to modify the curve at the points of junction of the observations 

 made in different positions. The general form is unaltered. It should 

 be mentioned that the point about which the curves appear to differ 

 most is near or at the change of exposure from the original observa- 

 tory to the temporary shed, about 1852. 



I may mention that I had not the slightest expectation, on first 

 laying down the curves, of any sensible agreement resulting, but that 

 I now consider the agreement too close to be a matter of chance. I 

 should, however, rather lean to the opinion that the connexion be- 

 tween the variation of mean temperature and the appearance of solar 

 spots is indirect rather than direct, that each results from some ge- 

 neral change of solar energy. 



I have forwarded these curves to you, knowing the great interest 

 you have ever taken in such inquiries, and on account of your being 

 the chief promoter of the establishment of a Meteorological Observa- 

 tory here. The problems of meteorology appear to be presented here 

 in a simpler form than in England ; and probably systematic photo- 

 graphic self-registering observations extended over a few years might 

 lead to important results. 



I have the honour to be, Sir, 



Yours obediently, 



E. J. Stone. 



Sir Edward Sabine, K.C.B., P.R.S., fyc. 



Resume of two Papers on Sun-spots : — " On the Form of the 

 Sun-spot Curve," by Prof. Wolf; and " On the Connexion of Sun- 

 spots with Planetary Configuration," by M. Fritz. By B. Loewy. 



Of these two series of investigations, one is by Professor Wolf, 

 the other by M. Fritz, communicated to Prof. Wolf. 



In the first, Prof. Wolf has proposed to himself to find the mean 

 character of the curve of sun-spots, i. e. its real form from one 

 minimum to another. He investigates the form only for 2J years 

 before, and 2| years after each minimum, and concludes by a simple 

 proportion of the remainder. He finds that the curve ascends more 

 rapidly than it descends — the ascent taking in the mean 3*7 years, 



