±20 
Proceedings of the Royal Society 
gruous. Becquerel’s observations * * * § were made under wood, and 
about a hundred yards outside in open ground, at three stations in 
the district of Montargis, Loiret. There was a difference of more 
than one degree Fahrenheit between the mean annual temperatures 
in favour of the open ground. The mean summer temperature in 
the wood was from two to three degrees lower than the mean sum- 
mer temperature outside. The mean maxima in the wood were 
also lower than those without by a little more than two degrees. 
Herr La Courf found the daily range consistently smaller inside 
the wood than outside. As far as regards the mean winter tempe- 
ratures, there is an excess in favour of the forest, but so trifling in 
amount as to be unworthy of much consideration. Libri found that 
the minimum winter temperatures were not sensibly lower at Flo- 
rence, after the Appenines had been denuded of forest, than they 
had been before.J The disheartening contradictoriness of his obser- 
vations on this subject led Herr Eivoli to the following ingenious 
and satisfactory comparison. § Arranging his results according to 
the wind that blew on the day of observation, he set against each 
other the variation of the temperature under wood from that with- 
out, and the variation of the temperature of the wind from the 
local mean for the month : — 
Wind, . . 
N. 
N.E. 
E. 
S.E. 
S. 
s.w. 
w. 
N.W. 
Var. in Wood, 
+ 0-60 
+ 0-26 
+ 0*26 
+ 0-04 
-0-04 
-0-20 
+ 0*16 
+ 0-07 
Yar. in Wind, 
-030 
1 
-2*60 
-330 
-1*20 
+ 1-00 
+ 1-30 
+ 1-00 
+ 1*00 
From this curious comparison, it becomes apparent that the 
variations of the difference in question depend upon the amount of 
variations of temperature which take place in the free air, and on 
the slowness with which such changes are communicated to the 
stagnant atmosphere of woods; in other words, as Herr Eivoli 
boldly formulates it, a forest is simply a bad conductor. But this 
* Comptes Kendus, 1867 and 1869. t See his paper. 
J Annales de Chimie et de Physique, xlv., 1880. A more detailed compari- 
son of the climates in question would be a most interesting and important 
contribution to the subject. 
§ Keviewed in the Austrian Meteorological Magazine, vol. iv. p. 543. 
