OX SUNSPOTS AND TERRESTRIAL PHENOMENA. 461 



in addition to this continued increase of damage done by lightning since 

 1833, there seems a clear connection with the sunspot" variation. The 

 years of maximum sunspots were 1837, 1848, 1800, and 1870; but we 

 tind minima in the per-centage of houses damaged in 1830, 1849, 1800', 

 and 1870. These are, however, not the only minima, but between each two 

 of them there is another, so that we generally have a comparatively small 

 number of houses damaged in the years of sunspot minima as well. In 

 other words, the curve of houses damaged shows with perfect regularity 

 a double oscillation for each sunspot period, the maxima of sunspots cor- 

 responding more closely to the better defined minima of lightning flashes. 

 It is curious that Fritz had come previously exactly to the same conclu- 

 sion in reducing the number of thunderstorms observed in the Indian 

 Ocean. He had then taken the result to be unfavourable to a connection 

 with sunspots ; but now that the same law is found to hold so accurately 

 in Bavaria, it certainly deserves very close attention. Professor von 

 Bezold has pointed out that the annual curve of thunderstorm frequency 

 shows a similar double period. There is a very decided maximum in 

 summer, but secondary maxima exist in January. It ought also not to 

 be forgotten that the auroroe show evidence of a similar double period. 

 During the years of minima of spots there is often a small increase in their 

 uumber. 



Harvests, Famines, and Commercial Crises. 



The question of harvests is principally of historical interest, for be- 

 fore the relationship of solar phenomena to torrestrial magnetism was 

 suspected, Sir William Herschel tried to find a connection between sun- 

 spots and the price of wheat. He came to the conclusion that the price 

 of wheat was generally higher at times of few sunspots. When Herschel 

 obtained these results, the periodicity of sunspots had not been disco- 

 vered, and he had therefore to take the years during which, as shown by 

 the records, sunspots had been looked for but not discovered, and to com- 

 pare them with the years which followed and preceded. The investiga- 

 tions which have been made since Herschel's time have not led to any 

 decisive results, and do not therefore deserve any more detailed account. 

 The wine harvests give, however, very curious results. I have pointed 

 out that the best years of Rhine wine in this century are all very close 

 to years of minima of sunspots. 1 The years 1783, 181 L, 1822, 1834, 1840, 

 1857, and 1805 are known for the quality of their wines ; and we have 

 sunspot minima in 1785, 1811, 1823, 1834, 1844, 1850, and 1807. 



Fritz has subjected the quantity of wine yielded by the vineyards in 

 Prussia to a careful analysis. The result proved a very decided period during 

 this century. The quantity was always larger in the period between a 

 sunspot minimum and the following maximum than at times of decreasing 

 sunspots. The numbers obtained for other countries give the same re- 

 sult, the years of largest quantity generally falling nea^, but a few years 

 previously to the sunspot maximum. If the quality is taken into account, 

 we find the best qualities preceding the years of greatest quantity, and 

 falling, therefore, as already pointed out, near the years of sunspot 

 minima. It is certainly a suggestive fact that the vine, which depends so 

 much on solar radiation for the proper ripening of its fruit, should show 



1 Mature, v., p. 501, 1874. 



