256 RESULTS OF COMPARATIVE OBSERVATIONS: SWITZERLAND. 



II. — Comparison of mean results of foregoing table. 



It appears from an examination of this table, that except in the winter 

 months the mean temperature of the woods is uniformly less than in the 

 fields, and that it is in most cases in summer cooler near the ground of 

 a forest than in the tree tops. The greatest difference was observed in 

 eTnly, except in the fir forest of Berne, where the difference was most in 

 April, both near the ground and at the tree tops. The greatest sym- 

 metry of curves (when these quantities are drawn upon a diagram)* oc- 

 curs in the beech forest. In all cases December is warmer near the 

 ground of a forest than in the fields, and here but little difference occurs 

 between trees of different kinds. A great and sudden decrease of differ- 

 ences in September and October is observed in all cases. 



Degrees above or below the mean of oi)en fields, at three Swiss stations. 



