On the Longevity of the Yew, 



31 



and fairest elements for the mean dimensions of its trunk, and 

 the base of the calculations of its age. They give an average 

 circumference of 25 ft. 6 in., and a diameter of 8 ft. 6 in., or 

 1224- lines. By De Candolle's method, its age is therefore 

 now 1224 years; and the mass of concentric zones of wood 

 which compose its trunk, when taken in the aggregate, ought 

 to have an average thickness of half a line, or 24 in each inch, 

 counted on a line drawn from the circumference to the centre ; 

 because, in measuring the diameter of the trunk, we take in 

 the two opposite sides of the same circle. 



To ascertain how far this rule might be relied on, I took 



