i".) Prof. Balfour Stewart and Mr. W. L. Carpenter. 



upon a galvanometer needle, a permanent source of power must exist ; 

 and as corrosion of metal does not occur, this source of power must 

 l>e different from that of the voltaic current ; such currents have been 

 attributed to capillary action. 



" Report to the Solar Physics Committee on a Comparison 

 between apparent Inequalities of Short Period in Sun-spot 

 Areas and in Diurnal Temperature-ranges at Toronto and 

 Kew." By BALFOUR STEWART, M.A., LL.D., F.R.S., and 

 WILLIAM LANT CARPENTER, B.A., B.Sc. Communicated to 

 the Royal Society at the request of the Solar Physics 

 Committee. Received April 21. Read May 1, 1884. 



1. It has been known for some time, through the researches of 

 Sabine and others, that there is a close connexion between 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 Baxendell, Meldrura, and various other meteorologists 

 have induced us to suspect that there may likewise be a connexion 

 between solar inequalities and those in terrestrial meteorology. 



This latter connexion, however, assuming it to exist, is not so well 

 established as the former at least if we compare together Inequalities 

 of long period. Attempts have been made to explain this by ima- 

 gining that for long periods the state of the atmosphere, as regards 

 absorption, may change in such a manner as to diminish or even 

 cloak the effects of solar variation by increasing the absorption when 

 the sun is strongest and diminishing the absorption when the sun is 

 weakest. 



On this account it has seemed to us desirable to make a comparison 

 of this kind between short-period Inequalities, since for these the 

 length of period could not so easily be deemed sufficient to produce a 

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



The meteorological element which we have selected for comparison 

 with sun-spots has been the diurnal range of atmospheric tempera- 

 ture an element which presents in its variations a very strong 

 analogy to diurnal declination-range. 



2. There are two ways in which a comparison might be made between 

 solar and terrestrial Inequalities. We might take each individual 

 variation in sun-spot areas and find the value of the terrestrial 

 element corresponding in time to the maximum and the minimum 

 of the solar wave. If we were to perform this operation for every 

 individual solar Inequality and add together the results, we 



