CV1 NOTES. 



months of December, January, and February, are taken as winter months, as 

 is both the usual and the most advantageous arrangement in meteorological 

 tables. When we compare the qualities of the wines of Franconia and Berlin, 

 and the mean summer and autumn temperatures of Wiirzburg and Berlin, 

 we are almost surprised to find that the temperatures differ only 1 or 1.2 

 of the Cent, thermometer, or about 2 of Fah. The spring difference is 

 greater, being about 2 Cent., or nearly 4 of Fah. The influence of late 

 May frosts on the flowering season of the vine, after a winter of correspondingly 

 lower temperature, is an element of no less importance than the late season of 

 the ripening of the grapes, and the influence of direct, not diffused, solar light 

 unobscured by clouds. The difference, alluded to in the text, between the true 

 temperature of the surface of the ground, and the indications of a thermometer 

 placed in the shade and protected from extraneous influences, has been 

 investigated by Dove, from the observations collected during fifteen years at 

 the garden of the Horticultural Society at Chiswick, near London, in Bericht 

 iiber die Verhandl. der Berl. Akad. der Wiss. August, 1844, S. 285. 



("f) p. 323. Compare my memoir, " iiber die Haupt-ursachen der 

 Temperaturverschiedenheit auf der Erdoberflache," in Abhandl. der Akad. der 

 Wissensch. zu Berlin atis dem Jahre, 1827, S. 311. 



C 398 ) p. 323. The general level of Siberia, between Tobolsk, Tomsk, and 



Barnaul, from the Altai to the ioy sea, is not so high as Manheim and Dresden ; 



and even Irkutsk, far to the east of the Jenissei, is only 208 toises (1330 



English feet) above the level of the sea, or about one-third lower than Munich. 

 ( 399 ) p. 325. Humboldt, Recueil d' Observations astronomiques, T. i. pp. 



126140; Relation historique, T. i. pp. 119, 141, and 227 ; Biot, in Con- 



naissance des temps pour Tan 1841, pp. 90 109' 



( m ) p. 327. Anglerius de Rebus Oceanicis, Dec. 11, Lib. ii. p. 140 (ed. 



Col. 1574.) In the Sierra de Santa Marta, the highest summits of which 



appear to exceed 18000 (above 19000 English) feet (Humboldt, Relat. hist. 



T. ii. p. 214), one peak is still called Pico de Gaira. 



( m ) p. 328. Compare the table of the heights of perpetual snow in both 



hemispheres, from 71 15' of North to 53 54' South latitude, in my " Asia 



centrale," T. iii. p. 360. 



I 402 ) p. 329. Darwin, "Journal of the Voyages of the Adventure and 



Beagle," p. 297 As the volcano of Aconcagua was not then in eruption, the 



remarkable phenomenon of the absence of snow cannot have been caused, as 



it sometimes is on Cotopaxi, by the rapid heating of the interior of the crater, 



