Part IV.] 
PRUNING AND THINNING. 
247 
had ceased. They were probably allowed to 
grow because, being many-headed, their timber 
was not valuable. 
Such trees, I believe, continue to exist for 
centuries, perhaps for thousands of years ; even 
after they are hollow. The old pollards which 
grace our forest grounds and commons were 
probably headed as young trees, and their 
growth cut periodically, as our underwood is 
now, the browsing of the deer and cattle neces¬ 
sitating in such places this sort of aerial coppice- 
wood. Charcoal was generally used before coal; 
and I think that the old pollards and the black 
circles of earth about Rotherfield, in this neigh¬ 
bourhood, may both be remains of the charcoal- 
burners of the forest, called by the Romans 
Anderida Silva, and by the Saxons Andredes 
Weald. 
However the heads of these pollards may be 
lopped, every year of life adds one ring of new 
wood and bark to the girthing of the stem. The 
same takes place when the tree is perfectly hol¬ 
low. The inside dead wood, being dry and im- 
porous, prevents the bleeding or efflux of the 
sap. I have found the girthing of some of 
these relics of the olden time much greater than 
the girthing of any sound timber I have ever 
R 4 
