902 TOTAL CLIMATIC INFLUENCE OF THE FOREST. 
by those who maintain that, as a meteorological agent, the 
forest is inert. 
The question of a change in the climate of the Northern 
American States is examined in the able Meteorological Report 
of Mr. Draper, Director of the New York Central Park Obser- 
vatory, for 1871. The result arrived at by Mr. Draper is, that 
there is no satisfactory evidence of a diminution in the rain- 
fall, or of any other climatic change in the winter season, in 
consequence of clearing of the forests or other human action. 
The proof from meteorological registers is certainly insufficient 
to establish the fact of a change of climate, but, on the other 
hand, it is equally insufficient to establish the contrary. Mete- 
orological stations are too few, their observations, in many cases, 
extend over a very short period, and, for reasons I have already 
given, the great majority of their records are entitled to little 
or no confidence.* 
* Since these pages were written, the subject of forest meteorology has 
received the most important contribution ever made to it, in several series of 
observations at numerous stations in Bavaria, from the year 1866 to 1871, 
published by Ebermayer, at Aschaffenburg, in 1873, under the title: Die 
Physikalischen Hinwirkungen des Waldes auf Luft und Boden, und seine Kit- 
matologische und Hygienische Bedeutung. I. Band. So far as observations of - 
only five years’ duration can prove anything, the following propositions, not 
to speak of many collateral and subsidiary conclusions, seem to be established, 
at least for the localities where the observations were made: 
1. The yearly mean temperature of wooded soils, at all depths, is lower than 
that of open grounds, p. 39. 
This conclusion, it may be remarked, is of doubtful applicability in regions 
of excessive climate like the Northern United States and Canada, where the 
snow keeps the temperature of the soil in the forest above the freezing-point, 
for a large part and sometimes the whole of the winter, while in unwooded 
ground the earth remains deeply frozen. 
2. The yearly mean atmospheric temperature, other things being equal, is 
lower in the forest than in cleared grounds, p. 84. 
3. Climates become excessive in consequence of extensive clearings, p, 117. 
4, The absolute humidity of the air in the forest is about the same as in 
open ground, while the relative humidity is greater in the former than in the 
latter case, on account of the lower temperature of the atmosphere in the 
wood, p. 150. 
5. The evaporation from an exposed surface of water in the forest is sixty- 
four per cent. less than in unwooded grounds, pp. 159, 161, 
