Part IV.] 
PRUNING AND THINNING. 
249 
The great secret of large timber is, centuries 
of non-cutting down, good soil, room, and shel¬ 
tered situation. These conditions rarely come 
together in cultivated countries, though they do 
sometimes in our old family places. The free 
growth and the enormous measurements of trees 
in the forests of uncultivated countries are more 
frequently to be attributed to the concurrence of 
the favourable conditions above stated, than to 
the peculiar attributes of the trees themselves. 
Such trees, when imported, and planted on the 
poor soils and exposed situations which are alone 
planted in cultivated countries, make moderate 
progress, and never reach any size. 
As long as countries are in a state of na¬ 
ture, trees, being the original possessors, seize 
on the valleys and best soils, from which they 
actually exclude man and cultivation. But the 
case is reversed when man has cleared the best 
soils for cultivation. Trees are then seldom 
planted or suffered to grow except on soils so 
bad as not to pay for cultivation. 
I have received the following marvellous mea¬ 
surements of some pinus Lambertianas on the 
Columbia, from an authority that I cannot 
doubt. At eight feet from the ground they 
were fifteen feet in diameter. The stems were 
