14 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
Dr Schlich summarises the effects on temperature as justifying 
the following conclusions :— 
“(1) The climate of forest countries is more equable than that 
of open countries. 
‘‘(2) The mean temperature of soil and air in forest countries 
is somewhat lower than that of soil and air in open 
countries. 
(3) The reduction of the temperature may act beneficially in 
hot countries, but it may be injurious in countries 
removed from the equator, where the temperature is 
already lower than is good for the ripening of field 
crops. 
“(4) Vegetation awakens later in spring in well-stocked forests 
than in open ground. 
““(5) As forests moderate the extremes of temperature, plants 
growing under the shelter of a forest crop are less 
liable to suffer from late and early frosts, or from 
drought, than plants growing in the open.” 
On the important question of the effect of forests on the mois- 
ture of the air, Dr Schlich summarises the data, chiefly German, 
which he discusses, by saying that “the mean annual excess in 
‘forests ranges from 3 to 10 per cent., which explains why dry 
‘‘currents striking through forests may become, in a short time, 
“relati¥ely moist, so that precipitation may be caused. At any 
“rate, there can be no doubt that the formation of dew is much 
“« greater in the vicinity of forests than on open ground away from 
“‘woodlands.” He shows that, although some 23 per cent. of the 
rainfall is intercepted by the crowns of trees in a forest, more 
of it actually penetrates the soil than does so in the open. 
Mechanically, it can be shown that of the rain falling on a 
forest, close on one-fourth is intercepted by the crowns of the 
trees, the other three-fourths falling on and being absorbed by 
the humus instead of running off in surface streams. Hygienic- 
ally, forests, Dr Schlich points out, assist in the production of 
oxygen and ozone, and usually improve the healthiness of a 
country. ésthetically, they may exercise a beneficial influence 
on man. 
Part II. discusses the “State in Relation to Forestry,” main- 
taining that it is for the State to guard the interests of the 
