49Q THE POPULAR SCIENCE MONTHLY. 



sociation between them. Nevertheless, I would not urge this with the 

 desire of in any way throwing doubt upon the opinion to which Prof. 

 Smyth has been led, knowing well that the long and careful examina- 

 tion he has given to this subject in all its details may have afforded 

 ample though not obvious evidence for the conclusions at which he 

 has arrived. I note, also, that, as he points out, Mr. Stone, director 

 of the Cape Town Observatory, and Mr. Cleveland Abbe, director of 

 the Cincinnati Observatory, have since, " but it is believed quite inde- 

 pendently, published similar deductions touching the earth's tempera- 

 ture in reference to sun-spots." All I would remark is, that the effect 

 is very slight, and very far from being obvious at a first inspection. 



Next as to rainfall and wind. 



Here, again, we have results which can hardly be regarded as 

 striking, except in the forcible evidence they convey of the insignifi- 

 cance of the effects which are to be imputed to the great eleven-year 

 spot period. We owe to Mr. Baxendell, of Manchester, the most com- 

 plete series of investigations into this subject. He finds that, at Ox- 

 ford, during the years when sun-spots were most numerous, the amount 

 of rainfall under west and southwest winds was greater than the amount 

 under south and southeast winds ; while the reverse was the case in 

 years when spots were few and small. Applying corresponding pro- 

 cesses to the meteorological records for St. Petersburg, he finds that 

 a contrary state of things prevailed there. Next we have the evi- 

 dence of the Rev. R. Main, director of the Radcliffe Observatory at 

 Oxford, who finds that westerly winds are slightly more common when 

 sun-spots are numerous than at other times. And, lastly, Mr. Mel- 

 drum, of Mauritius, notes that years of spot-frequency are character- 

 ized, on the whole, by a greater number of storms and hurricanes than 

 years when the sun shows few spots. 



The association between the sun-spot period and terrestrial mag- 

 netism is of a far more marked character, though I must premise that 

 the Astronomer Royal, after careful analysis of the Greenwich magnetic 

 records, denies the existence of any such association whatever. There 

 is, however, a balance of evidence in its favor. It seems very nearly 

 demonstrated that the daily sway of the magnetic needle is greatest 

 when sun-spots are numerous, that magnetic storms are somewhat 

 more numerous at such times, and that auroras are also more com- 

 monly seen. Now, it has been almost demonstrated by M. Marie Davy, 

 chief of the meteorological division in the Paris Observatory, that the 

 weather is affected in a general way by magnetic disturbances. So 

 that we are confirmed in the opinion that, indirectly, if not directly, the 

 weather is affected to some slight degree by the great sun-spot period. 



Still, I must point out that not one of these cases of agreement has 

 any thing like the evidence in its favor which had been found for an 

 association between the varying distance of Jupiter and the sun-spot 

 changes. For eight consecutive maxima and minima this association 



