ON SINsroTS AND TEllRKSTItlAI, rUKNOMKNA. 



447 



ooiuioction by a strictly stntisticiil in(|niry. We arc, further, not todisctHs 

 whether the eoiinoctinn, it' it, exists, is siillicieiitly liir^'c to alVect mntei-ially 

 the character of our siiiumers or of our winters. The scientific interest 

 is the sanio wliether the iulliu'iice be larn'c oi- small ; and thouu;h the (lil- 

 lerence in temperature helween years of maximum and years of niinimniri 

 suiispots niiiy only bo tiio hundredth part of a deij^ree, wo must bo satis, 

 tied with the rcsnh as soon as it has been sulHciently well established. 



Tew pcoplo only are aware of the many careful and unprejudiced 

 invest illations that have been made on the sid)ject ; and there is a pjreat^. 

 ileal of misconception, even amonn^ tliose who take a special interest in 

 it, as to the uniform drift of these investii;ations. There can no longer 

 l)e a (ioubt that during about four sunspot periods (IHIO iH(iO) a most 

 iciiiarkable similarity exists between the curves repi'csentintJ^ sunspot, 

 liviiiieiicy and the curves of nearly every meteorologiciil pheiunnenon 

 which is related to temperature. This is not, in my opinion, a matter 

 open to discussion : it is a fact. But it is equally certain th.at durinr; the 

 thirty or forty years previously to that tinu) no such relaf ionshij) exists, 

 and that .«*iuco l'S<)U the connection has again, in some cases, become less 

 distinct. The rpiestion v/hieh arises now is tliis : Does the ab.^enco of 

 uiiy iipparont connection at tlio beginning- of this, and es|)ecially at tho 

 end of last centurj', which, as far as we can judge, may be ])artially ve- 

 lu'nted at the present time, render it probable that tlu; relationship which 

 held godd foi- nearly, if not quite, half a century, is only accidental ; or is 

 it more reasonable to suppose that there is a ti'ue connection, but tliat 

 other causes are at Avovk sufliciently strong altogether to hide the regii- 

 hu'ity for a succession of years at a time? This is a [)oint on whii-h 

 everybody will follow tho dictates of his own eomrat)n sense, and on 

 which, therefore, wo must not expect any unanimity of opinion. In 

 givin<4' an account of the work which has been done, and of the ([uestions 

 which are jiending, I shall not attempt to mention, much less to snm- 

 luarisp. every i)aper that has been written on the subject. There is hardly 

 one on which we pos.sess more exhaustive summaries, and to them 1 must 

 ivfiT tlie reader who wishes a more detailed account.' 





ii! 



RiiilHcihin of Suv,«pnt Maamromerds. 



h\ order to compare terrestrial phenomena with sunspot activity, we 

 must finst obtain a numerical measure of thataetivit}'. iMessrs. Do La Hue, 

 Stewart, and Loewy have in their researches measured the spotted area, 

 of tho sun : and recent) v the ' Solar Phvsies Committee ' has deduced, as far 

 as possible, this area fi'om the measurements of Schwabe and Carrington. 

 The spotted area of the sun, no doubt, is at present tho most eciontitit; 

 iiieasuro of solar activity ; but wo do not possess the necessary data for 

 its determination except for a very limited period. For the older obser- 

 vations, then, at any rate, we must be satisfied Avitli a simpler measure, 

 and it has become customary to adopt Wolf's so-called sunsjDot numbers, 

 •llie san.spot number for a certain day, according to "Wolf, is k (/-flU^), 



' F. G. Hahn: Uther tlir Jlczu'huDpen dor StiniiPiifli'fJ.TnprHddr zn metcorohfiiitchrn- 



t'fichbningrn. (Leipziu', 1.^77.) Hermann Fritz ; D'm JSczh-hiinijrn dcr iSo/i/n-n- 



firl.rii zii den mai/nrtitir/ii'n iind Jiicfrorolof/isclii'n £rnclu'i/n/n//rit dcr Erdc (^Xatiirli. 



^'■rh.d.holl. Maatsch. H7,s.<. Haarlem, 1878.) Siogmund (J iiut her : i>cr .£'<V//^«i(s 



<i>:r Uimmclsli0)'2)cr avj Wittcnmgsverhultnisnv, Niirnberg, 1884. 



Ill 



