TT. lY. 



PKUNING AND THINNING. 



219 



diameter, and gives it the astounding and patriarchal 

 age of 5,150 years. This would be very slow growth ; 

 scarcely more than the twenty-ninth part of an inch 

 for the width of each annual ring ; that is, if the width 

 of the annual ring were the twenty-ninth part of an 

 inch, the tree would attain the diameter of thirty feet 

 in 5,220 years, or in seventy years more than the sup- 

 posed age of the tree. 



The age of this identical baobab, then, at Noah's 

 deluge, being short of 1,000 years, its diameter would 

 be short of six feet, and its girthing perhaps seventeen 

 feet ; not an inconsiderable plant certainly, but small 

 for so great an irrigation. Adanson's guess was made 

 by cutting into the stem of the tree till the width of 

 three hundred rings was measured. ' The average 

 rate of growth of younger trees of the same species 

 was then ascertained, and the calculation made ac- 

 cording to a supposed mean rate of increase.' I quote 

 from the admirable Lyell, who quotes the ' Biblioth. 

 Univ.' on the longevity of trees. 



If the general average width of the rings, which 

 included the growth of the young trees, was only the 

 twenty -ninth part of an inch, what was the average of 

 the first three hundred rings, which were all old 

 growths ? Perhaps the fiftieth part of an inch. But 

 Adanson should have given us these data, and his 

 mode of calculation from them. I cannot help thinking 

 that he may have made a slight mistake in these cal- 

 culations ; that he may have omitted to perceive that, 



