20 The Forest of the Ancients. 
posed all bodies: the more fire in the composition of a 
wood, the more readily would it decay. Spruce being 
composed of less earth and water, but more fire and air, 
is therefore lighter than oak which, mostly composed 
of earth, is therefore so durable; but the latter warps 
and develops season splits because on account of its 
density it cannot take up readily and resists the penetra- 
tion of moisture. 
Wood impregnation, supposed to be a modern inven- 
tion, was already practiced; cedrium (cedar oil) being 
used as well as a tar coating or immersion in sea- 
water for one year, to secure greater durability. 
While then the .ancients were not entirely without 
silvicultural knowledge, indeed possessed much more 
than is usually credited to them, the need of a forest 
policy and of a systematic forest management in the 
modern sense had not arisen in their time; the mild 
climate reducing the necessity of fuelwood and the 
accessibility by water to sources of supply for naval and 
other construction delaying the need for forest produc- 
tion at home. 
There is little doubt, that some of the agricultural 
and silvicultural knowledge and practice of the Romans 
found entrance among the German tribes who, espe- 
cially the Allemanni, came into contact with the Romans 
in their civilized surroundings during the fourth cen- 
tury. 
