December 26, 1884.] 



$CIEN8E= 



565 



the variations in the sun-spot data correspond 

 exactly to those relating to the element under ex- 

 amination, we shall be compelled to admit some 

 sort of a causal connection ; and that, even if the 

 nature of the connection is inscrutable. 



Numerous such comparisons have been made 

 during the past twenty-five years. So far the re- 

 sults must be pronounced indecisive, except as 

 regards the effects of solar disturbances upon ter- 

 restrial magnetism. Here all the investigations 

 agree in showing an intimate connection, the mech- 

 anism of which is, however, still unknown. When 

 sun-spots are numerous and active, we always have 

 magnetic storms upon the earth, manifested by the 



<~ 



^ ' 



Wr-rt 



;V 



; : , ?)■ 



vy. 



X-- 



| 





■ ■:V.'V^.' i 



m 



ill 



i'-v v'^ •- 





£0l$?£* 





















;\ ■ ,■•■ 







'.H-'Cv-p- ';.■■.. .- 





































;0 <•• 



£s 



: v 



.-,• ■ & 



■'-~'Y. i']' : --\\ 



■•'■/,.- 





'% 



fM&Sy'-- 



m^-' 



m.?-% 



K«liS 







:•■& 





Ecirth 



SUN-SPOT AS SEEN JULY 25, 1883. 



aurora-borealis and by strong disturbance of our 

 compass-needles. 



The investigations in regard to other elements 

 have, as Professor Langley says, "nearly every 

 one brought out some result which might be plausi- 

 ble if it stood alone, but which is apt to be contra- 

 dicted by the others." For instance : Dr. Gould 

 in South America, and Mr. Stone at the Cape of 

 Good Hope, think they have detected a slight low- 

 ering of temperature, amounting to one or two 

 degrees, at the time of sun-spot maximum ; while 

 at Edinburgh, Smyth reaches a similar conclusion, 

 except that the minimum temperature follows the 

 sun-spot maximum at an interval of about two 

 years. On the other hand, Chambers, from twenty- 

 eight years' observations in India, finds a rise of 

 temperature coinciding with the sun-spot maxi- 

 mum ; and, in opposition to all the others, Jelinek 



of Prague, from all the observations he could col- 

 lect in Germany up to 1870, obtained a purely 

 negative result. Discrepancies of the same sort 

 appear in the results of other investigators, with 

 reference to the rainfall and the height of rivers in 

 different parts of the earth ; though, on the whole, 

 they seem to show a slight increase in the rainfall 

 (one or two per cent) at or near the time of spot- 

 maximum. 



It is to be remarked, however, that these dis- 

 crepancies and contradictions by no means dis- 

 prove the reality of sun-spot influence. It is quite- 

 possible, and even likely, as Dr. Gould and others 

 have pointed out, that slight changes in the sun's 

 radiation might be felt 

 mainly by their effect in 

 disturbing atmospheric cur- 

 rents, and so altering the 

 distribution of heat and 

 moisture, rather than by 

 any general effect. In this 

 case, the effects in neigh- 

 boring regions would evi- 

 dently be exactly opposite 

 in character. 



As matters stand, it is 

 clear, in the first place, that 

 a much longer period of 

 observations will be needed 

 to settle the question de- 

 cisively as to the reality of 

 sun-spot influence ; and, in 

 the next place, that, if the 

 influence is real, it is only 

 slight, and so masked by 

 other effects as to be difficult of detection. There 

 can be no reasonable expectation that the ordinary 

 variations in the state of the solar surface will prove 

 to be dominant, or even very important, in terres- 

 trial meteorology, or in human conditions that de- 

 pend upon climate and the weather. 





mm. 



THE INSECTS OF THE YEAR. 



" Fairy bands 

 Sailing, 'mid the golden air, 

 In skiff's of yielding gossamer." 

 Hogg. 



The seasonal appearance of insects varies. 

 Some species are found during several months, 

 others at all times of the year; some vary in date 

 of appearance with the earliness or lateness of the 



