(( 



A FEW NOTCHES ON OLD TREES." 197 



quite out of court if B.C. trees are in existence. That if an 

 existiug banyan tree (to wliich I have alluded) sheltered 

 the hosts of Alexander, say 300 B.C., it must have been 

 a very old tree then, and 3,000 years could not be an over- 

 estimate of its age. Decandolle, judging from the size and 

 growth of the baobab trees (Adansonias), considered that 

 some of these ought to be computed to be 5,000 years old ! 



Then, I think, we must admit there are yews which are 

 between 2,000 and 3,000 years old. How are these estimates 

 made ? 



As a rule a forest tree makes a woody circle every year, and 

 therefore, if you count the concentric rings in any through 

 section of a tree or branch, you ought to be able to calculate 

 their respective ages, and yoa could tell when the branch 

 was given off from the parent stem. In some years, however, 

 and with some trees certainly, instead of one ring we may 

 have two or three formed, owing most likely to unusual 

 alternations of heat and cold. This condition would bring 

 about over-computation. Against this may be set the fact 

 that in some years, owing to the peculiarities of the seasons, 

 or damage done by very severe frosts, no ring may be 

 formed in that year. 



With regard to sequoias and red-woods, we know from 

 experiments that they may form several concentric woody 

 circles in some years. Then, certain marks have been found 

 in trees after they have been cut down, which have estab- 

 lished the periods of growth since. Thus, in felling and 

 sawing up some of the old trees in Sherwood Forest, letters 

 were found within the wood of several — depressed letters in 

 one circle, and then the next year filled up the depressions 

 corresponding to the incisions with new woody fibre. Thus 

 in one tree was found a crown carved with " W. M," for 

 William and Mary. In another, " I," with a crown, peculiar 



