392 



MM. Wolf and Fritz on Sun-spots. [Mar. 23, 



both of the solar spots near the minimum, 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 pheno- 

 mena 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 

 temperature resulting from the observations in the temporary Observatory, 

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

 ordinates, therefore, will be depressed too much relatively to those corre- 

 sponding to observations made in the other two observatories. In the 

 curve 2, I have imperfectly corrected the mean of the results for the tem- 

 porary 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 observatory 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 con- 

 sider the agreement too close to be a matter of chance. I should, however, 

 rather lean to the opinion that the connexion between the variation of 

 mean temperature and the appearance of solar spots is indirect rather than 

 direct, that each results from some general 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 Observatory here. The 

 problems of meteorology appear to be presented here in a simpler form 

 than in England ; and probably systematic photographic 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. 



III. Resume of two Papers on Sun-spots : — u 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. Communicated by Warren De La Rue, F.R.S., 

 and B. Stewart, F.R.S. 



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

 by M. Fritz, communicated to Wolf. 



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

 racter of the curve of sun-spots, i. e. its real form from one minimum to 

 another. He investigates the form only for 2| years before, and 2| years 



