PORTION OF THE COSMOS. THE SUN. 277 



1695 to 1700; and from 1795 to 1800; with the prices of 

 com and the complaints which had been made of bad 

 harvests ( 4 ? 3 ). Unfortunately, however, the knowledge of 

 the numerical elements required to furnish the base of even 

 a conjectural solution of such a problem must always be 

 wanting; not only, as Herschel himself justly remarked, 

 because the price of corn in one part of Europe cannot 

 afford a standard whereby to judge of the state of vegetation 

 over the whole continent, but also and more especially, be- 

 cause we can by no means infer from a diminution of the 

 mean temperature of the year extending even over the whole 

 of Europe, that in that year the globe generally had re- 

 ceived a less quantity of warmth than usual from the Sun. 

 Dove's investigations on the non-periodic variations of tem- 

 perature have tended to show that " oppositions," or con- 

 trary states of weather, are always placed laterally side by 

 side, in the same, or almost the same, parallels of lati- 

 tude. Thus our continent and the temperate part 

 of North America are usually opposed to each other 

 in this respect, so that if we have an abnormally 

 severe winter, the winter there will be milder than in 

 ordinary years, and vice versa. Seeing the unquestionable 

 influence of the mean amount of summer heat on the 

 cycle which vegetation passes through, and therefore on the 

 success of cereal crops, we must regard such compensa- 

 tions in the distribution of temperature, over parts of the 

 globe united by easy and convenient communication by 

 sea, as productive of highly beneficial consequences to 

 mankind. 



While "William Herschel attributed to the activity of the 

 central body, manifested in the processes of which the solar 

 spots are results, the effect of an increase in the temperature 



