Warxer.—State Forestry: its Aim and Object. 199 
of artificial forests throughout the mining districts of Otago, from which I 
have just returned, the advantages both direct and indirect, will, I am sure, 
be readily admitted by all who have visited that treeless region. Much has 
been written on the subject of the influence of forests on rainfall, springs or 
streams of water, and the humidity of the atmosphere generally. I do not 
think we can consider it proved that their existence or non-existence influ- 
ences in any appreciable degree the total rainfall of a district, although they 
probably do cause the clouds to precipitat thei isture in certain localities.* 
As to their favourable influence in the case of springs and streams there 
is little doubt, and many instances could be quoted from Von Humboldt, 
Marsh on “ Man and Nature," and other standard works. They not only 
prevent excessive evaporation, but, by their presence and action, render 
the flow of water more regular and permanent, thus preventing disastrous 
floods and torrents during the winter or rainy season, and long droughts in 
summer. Their removal from mountain tops and hill sides cannot but be 
regarded as an evil, often followed by the most disastrous results. So 
much has this been found to be the case in France that they are now 
engaged in a gigantie work of replanting the slopes of the Alps and Pyrenees, 
which had been cleared in former years for grazing. Those replantings 
are to extend over 200,000 English acres, to cost £400,000, and the work 1s 
estimated to extend over 140 years, which is considered “not an unreason- 
able time to undo the work of twenty centuries." Only fourteen years of the 
140 have as yet expired, and £40,000 has been expended in replanting 
G: reboisements ’’) at the points most threatened, and, I am glad to learn, 
with the best results. Extensive planting is also being carried on in the 
Landes, and district of the Gironde. 
The latest contributions to our forest literature on the subject 
of the influence of forests on climate, is, I think, given in the 
reports of the Forest Conference held at Simla in October, 1875, 
in the shape of a translation from a paper by M. J. Clavé, which 
appeared in the Revue Des Deux Mondes, from which I extract the 
following :—‘‘ There are four separate actions of nature through which it 
may be said that forests influence, in some way or other, the physical con- 
ditions or climate of a country. 1st. There is a chemical action through the 
leaves in decomposing the carbonic acid of the air. 2nd. A physical action 
in retaining moisture in the earth, and in checking the violence of the wind. 
8rd. A physiological action in transmitting to the air through the leaves 
* Hof Rath Wex, in a paper on the ‘ Decrease of water in rivers and springs,” com- 
municated to the Vienna Geographical Society in 1875, states that the decrease of water 
in the Elbe and Oder has been seventeen inches ; in the Rhine, twenty-four; Vistula, 
twenty-six ; and Danube, at Orsova, filty-five inches in fifty years. 
