30 On the Heat of Springs, [July, 



of the absence of those conductors of heat which are to be found 

 in mosses, bogs, and morasses. Hence the plants which cover dry 

 declivities on high mountains, in warmer places appear only in deep 

 morasses, because it is only in such places that they find the low 

 temperature which they require. This is the case with heiida nana, 

 andromeda polifolia, narthec'mm boreaie. In Switzerland these 

 plants do not rise to the higher mountains. Perhaps the morass of 

 Skateldf, in Smoland, in which we so unexpectedly meet with 

 letula nana, is cooled by means of springs, which oppose here the 

 influence of the sun's rays more than in other places. To this want 

 of conductors of heat, either immediately, or through the failing 

 of the circulation of water, and the consequent low temperature of 

 the place, is to be ascribed the great art and trouble requisite to 

 render the northern provinces of Sweden equally fruitful as tempe- 

 rate climates. In Lapland the driest places only are fit for the pur- 

 poses of agriculture. 



II. 



On the Temperature of the Springs at Upsala in the Year 1810. 

 By George Wahlenberg. 



We seldom find springs which undergo a great alteration in their 

 temperature, and yet in dry and wet years furnish an equal quantity 

 of water. Such, however, is the case with the spring at Lassby- 

 lackar. There are two veins of water, the southernmost of which 

 rises immediately out of the sand. I found the changes in its 

 temperature as follows : — 



Spring at Lassbybackar, near Upsala. 



1809— 1 November 44-96° 1810— 1 May 34-16® 



5 43-88 



11 42-62 



20 40-46 



29 38-81 



5 December 38-48 



13 38-4S 



22 37-40 



24 37-58 



1810 — 4 January. . 37*40 

 19 36-68 



27 .* 36-50 



6 February. 36-14 

 8 36-05 



12 36-05 



22 35-42 



4 March.. . 35-06 



13 34-70 



25 April 34-16 



28 34-16 25 44*24 



Mean of the whole year 41"72 



o 



