ASTRONOMY. 181 



JSun-spots. — " l\ei)ort to the Solar Physics Committee on a Comparison 

 between Apparent Inequalities of Short Period in Sun-spot Areas and 

 in Diurnal Temperature Eangesat Toronto and at Kew.' By Balfour 

 Stewart, M. A., LL.D., F. E. S., and William Lant Carpenter, B. A., B. Sc. 

 Commuuicated to the Eoyal Society at the request of the solar physics 

 committee. 



It has been known for some time that there is a close connection be- 

 tween the inequalities in the state of the sun's surface as denoted by 

 sun-spot areas and those in terrestrial magnetism as denoted by the 

 diurnal ranges of oscillation of the declination magnet; and moreover 

 the observations of various meteorologists have induced us to susjject 

 that there may likewise be a connection between solar inequalities and 

 those in terrestrial meteorology. 



This latter connection, however (assuming it to exist), is not so, well 

 established as the former, at least if we compare together inequalities 

 of long i^eriod. It has been attempted to explain this by imagining 

 that for long periods the state of the atmosphere as regards absorption 

 may change in such a manner as to cloak or diminish the effects of solar 

 variation by increasing absorption when the sun is strongest, and di- 

 minishing absorption when the sun is weakest. 



On this account it seemed desirable to the authors to make a com- 

 parison of this kind between short-period inequalities, since for these 

 the length of period could not so easily be deemed sufiQcient to produce 

 a great alteration of the above nature in the state of the atmosphere. 



The meteorological element selected for comparison with sun-spots 

 was the diurnal range of atmospheric temperature, an element which 

 presents in its variations a very strong analogy to diurnal declination 

 ranges. 



It is such a comparison that the authors have made, their method of 

 analysis being one which enables them to detect the existence of un- 

 known inequalities having apparent periodicity in a mass of observa- 

 tions. A description of this method has already been published in the 

 Proceedings of the Royal Society for May 15, 1879. The comparison was 

 made by this method between sun-spot observations extending from 

 1832 to 18G7,' inclusive, Toronto temperature-range observations ex- 

 ten«ling from 1844 to 1879, inclusive, and Kew temperature-range ob- 

 servations extending from 1856 to 1879, inclusive. The following con- 

 clusions were obtained from this comparison: 



1. Sun-spot inequalities around twenty -four and twenty-six days, 

 whether apparent or real, seem to have periods very nearly the same 

 as those of terrestrial meteorological inequalities as exhibited by the 

 daily temi)eratu re-ranges at Toronto and at Kew. 



2. While the sun-spots and the Kew temperature-range inequalities 

 present evidence of a single oscillation, the corresponding Toronto 

 temperature-range inequalities present evidence of a double oscillation. 



3. Setting the celestial and terrestrial members of each individual 



