1814.] Limits of perpetual Snow in the North. 349 



If we compare the mean annual temperature at Uleoborg with 

 that at Upsala, we shall find them to rise and fall together, as the 

 following little table will show : — ■ 



Mean Yearly Temperature. 



At Uleoborg. Therm. At Upsala, Therm. Difference. 



1776 -0-9° Centigrade +6-18° Centigrade 7-08 



1777 -2-2 4-25 6-45 



1778 -2-5 4-89 7-39 



1779 -0-9 7-36 8-26 



1780 -3-4 470 8-1 



I78I -3 5-98 8-98 



Mean -2-15 + 5-54 7-686 



1782 —0-1 4-444 4-5 



1783 -2-5 5-7 8-2 



1784 — 1-9 3-54 5-44 



1785 + 0-5 3-84 3-3 



1786 I 4-07 3-07 



1787 1-9 5-15 3-25 



Mean 0-183 +4-456 4-633 



There is a striking discordancy between the differences in the 

 first six and last six years of this table. But at the beginning of 

 1782 Mr. Julin laid aside the spirit of wine thermometer, and 

 began to observe with Hasselstrom's mercurial thermometer. It 

 would appear that notwithstanding his endeavours to correct the 

 spirit of wine thermometer, it stil! stood lower than the mercurial 

 one. On that account, if we reject the first six years' observations 

 altogether, the mean temperature at Uleoborg will be as I have 

 given it in page 344. 



2. On the Height at which different kinds of Trees grow. 



The hopes which I have held out in the preceding dissertation, 

 that the difference in the heiglit to which the different trees extend, 

 which in Lapland is so constant, will be found to be equally so over 

 the whole earth, are completely visionary. During my journey in 

 Switzerland and Savoy in 1810, I observed quite a different state of 

 things. The summer in Lapland and on the Alps is very dissimilar, 

 and the monks of St. Bernard are in the right when they say, "The 

 inhabitants of Lapland are fortunate, much more fortunate than 

 we; they enjoy a warm sunnncr favourable to life, while our summer 

 is only a milder winter." Dr. Wahlenberg, in his Flora Lnfjponica, 

 has placed this difference clearly before our eyes, by his exhibition of 

 the curves n presenting the temperatures at Eiionlekis in Lajiland, 

 and at the cloister on St. Gotthardt. Tlie effect which this differ- 

 ence must have upon the height to which trees vegetate, he has 



