238 FORESTRY IN FRANCE. 
can frame without interference with their ordinary duties; but 
they undertake the revisions, which are made every ten or fifteen 
years in order to guard against errors, and to allow for changes 
in the rate of growth, or other causes of disturbance. Pending the 
preparation of such regular plans, the Forest Department draws up 
provisional rules, which must accord with local usages, where these 
are not opposed to the recognised principles of sylviculture. Up 
to the beginning of 1877 regular working plans had been com- 
pleted for more than two-thirds of the total area of the State 
forests, and for somewhat less than one-half of the communal 
forests. The work progresses more slowly in the latter than in the 
former, because in their case the funds have to be provided by the 
communes, and the money is not always available; but as a matter 
of course the most important forests were taken in hand first, and 
these have for the most part been completed. 
The question of working plans has only been dealt with above in 
an extremely superficial manner. In order to gain anything like a 
complete idea of the systems pursued in France, the following works 
should, among others, be studied, viz,: ““Aménagement des foréts,” 
by C. Broillard, Berger-Levrault, Paris, 1878, and ‘ Aménagement 
des foréts,” by A. Puton. A translation of the latter work has 
appeared in vols. viii. and ix. of the ‘‘ Indian Forester.” 
PrRopucTS OBTAINED FROM THE FORESTS. 
The yield in wood of various classes having once been fixed by 
the working plan, it is the business of the department to realise it 
as nearly as circumstances will permit. As to tanning bark, all that 
the felled trees or poles will yield is utilised. Cork bark is taken 
from the living trees, which will not bear the removal of a too 
large proportion of their protective covering, and hence care has 
to be taken not to overwork them. Resin is collected on a large 
scale in forests of the maritime pine (Pinus maritima), which only 
yield it freely on the hot and damp coasts of the south-west. 
The yield of minor produce, such as grass, moss, litter, and other 
things, being small, and details regarding it not being available, 
this class of products cannot receive more than a passing mention. 
Neither can account now be taken of the numerous advantages 
which the forests undoubtedly render to the population, but which 
cannot be expressed in the bulk or weight of the products drawn 
from them. . 
The latest available statement of yield relates to 1876, in which 
