46 



NA TURE 



[May 17, 1877 



Here we have evidence from various quarters of a con- 

 nection of some sort between the state of the sim's sur- 

 face and the meteorology of the earth, and it becomes a 

 question of great interest what is the nature of this 

 connection. 



In the first of these articles a diagram was exhibited 

 showing the close relation that exists between the stale of 



the sun's surface and the range of oscillation of the magnet 

 freely suspended at the Kew Observatory. If instead of 

 taking the daily magnetic ranges we take the daily tem- 

 perature ranges, that is to say, the differences between 

 the maximum and minimum thermometers, we find an 

 apparent reference to the state of the sun in these also, 

 inasmuch as these ranges appear to be greater at times 



Dl/CRAM K — Tlie Upper Cu 



. Temperature Ranee, the Lower Curve Declination Range. 



of maximum than at times of minimum sun-spot frequency. 

 Nevertheless the correspondence is not nearly so well 

 marked as in the case of the ma;:;netic declination, and 

 there is no doubt much local irregularity. But here the 

 following question of much interest and importance crops 

 up. Do these fluctuations of the daily temperature range 

 at the Kew Observatory coincide in point of time with 

 the corresponding solar fluctuations .' or do the former lag 



behind the latter, as is the case with the magnet ? The 

 practical bearing of this question is easily seen, for if tem- 

 perature oscillations and other meteorological fluctuations 

 are simultaneous with the corresponding solar changes, 

 we can hardly expect that a study of the sun's surface 

 will ever enable us to forecast meteorological occur- 

 rences: but if on the other hand the solar changes 



precede the meteorological ones, we may hope, when the 

 nature of the connection between them is fully understood, 

 to make use of solar observations in order to predict the 

 greater meteorological occurrences. Now it appears to the 

 writer that there are certain well-marked fluctuations of 

 temperature range at the Kew Observatory which coincide 

 very closely with corresponding magnetic fluctuations, and 

 which therefore lag behind the solar fluctuations nearly six 

 months (see Article I.) ; but this 

 interesting and important question 

 can only be determined by further 

 investigations. 



I may here remark that meteoro- 

 logists are beginning to suspect a 

 somewhat intimate connection be- 

 tween the magnetism and the meteo- 

 rology of the earth. Mr. Baxendell 

 was, I think, the first to point out 

 that there is a diurnal inequality in 

 the direction and velocity of the wind 

 apparently connected with the daily 

 changes of magnetic declination. On 

 this subject the writer has recently 

 received a letter from Mr. J. A. 

 Broun, the well- known meteorologist 

 and magnetician, who says, "My 

 present opinion is that meteorological 

 phenomena are due to solar actions ; 

 that the heating action is not the only one ; but that 

 the action which produces variations in the earth's mag- 

 netic force affects the conditions of the atmospheric gases, 

 introducing forces which we cannot in the present state 

 of our knowledge appreciate, though the facts appear to 

 me to prove their existence." 



It will be seen, by Diagram K, that there is a very 



