32 On the Longevity of the Yew. 



three horizontal sections from different sides of the trunk *, 

 the average number of rings in each of which is as follows: — 



Section on the North Side. Section on the South Side. 



Rings in 1 in. of the diameter - 44 Rings in 2\ in. of the diameter 1 18 



Ditto - ditto - - 36 Ditto on opposite side of the 



Ditto in £ in. 45, say in 1 in. 50 50 sjme section - - - 113 



3)130 5)231 



Average number per inch - 43 Average number per inch - 46 



A section taken on the s.w. side, from a projecting portion 

 of the trunk, where the rings were swollen beyond their ordi- 

 nary thickness, contained only 15 within the inch, and were 

 so uniform as not to require an average to be taken. 



Average number of rings per inch on the north side - - 43 

 Ditto ditto on the south side - - 46 



Ditto ditto on the south-west side - 15 



3)104 



General average number per inch of diameter - 34f 



Therefore, a yew whose diameter is 8 ft. 6 in., supposing 

 each inch of the radius to contain 34 rings, would consist of 

 1734 such annual rings, and be, at least, that number of years 

 old. But this would exceed the truth ; because I have shown 

 that young yews deposit thicker layers than older ones, and a 

 corresponding allowance must be made. Now, as there are 

 eio-hteen yews growing in the same churchyard, whose ages are 

 knownf, and whose average diameter, at 120 years old, is 20 in., 

 we cannot do better than to assume that the great yew now 

 under consideration had a similar diameter at that age, and, 

 farther, that it continued to increase in the same ratio up to 

 150 years, the date assigned by De Candolle for the diminu- 

 tion of its rings. I would also make an additional allowance 

 for a probable intermediate rate of increase between the age 



* Some of my sections have been taken with a frame saw, and others 

 with a circular one, similar to the trephine, made for me by Mr. Salt, sur- 

 gical instrument maker, Birmingham. The latter is worked horizontally, 

 with a carpenter's brace, and is decidedly the best, as it takes out a clean 

 cylinder of wood 3 in. deep, which, when divided longitudinally, shows the 

 annual rings throughout its whole length, and the hole may be plugged up. 

 The greatest difficulty is to detach the base of the cylinder, and extract it ; 

 it has, besides, too much friction, and, in its present state, is only applicable 

 to very hard wood, though I hope to adapt it to all. 



f 1 have caused the situation and present dimensions of each of these 

 trees to _be inserted in the parish register, to form data whereby their 

 future increase mav be ascertained. 



