S38 Prof. De CandoUe (wi the Longevity of Trees, 



diametrical increase of old trunks, and, compared with other 

 measurements, would give approximate averages for estimating 

 their ages. Thus, in Evelyn, we find, that in 1660 there was 

 an immense oak in Wellbeck Lane, which was 33 feet 1 inch 

 round, about 11 feet perhaps in diameter. The same oak, though 

 greatly mutilated, existed in 1 775, and was 12 feet in diameter ; 

 of course, it had increased about 144 lines in 120 years, a little 

 more than one line annually. From this we may conjecture 

 that the law of increase indicated by the oak of 333 years in 

 my Table, is followed by this one, though evidently older. If, 

 therefore, we calculate the age of the oak in Wellbeck Lane, 

 we see by the thickness of that of 333 years, that it must have 

 been about 1300 years old when Evelyn lived, and more than 

 1400 in the year 1775. 



5. Lastly, in cases where it is impossible to obtain a trans- 

 versal cut of an old tree, it may happen that we may have an 

 opportunity of making a lateral cut in the tree, in order to 

 ascertain how much it has increased in a given number of years, 

 and in this way find out the minimum of its mean increase. It 

 was by this process that AdanBon discovered the age of the 

 Baobabs ; he saw the extent of the growth of these trees in three 

 centuries, and also knowing the growth of young trees, he was 

 enabled, by striking an average, to establish the general law. 

 The age of the Taxodium of Chapultepec in Mexico should be 

 carefully investigated by this plan. 



By means of the five plans, either singly or connected, 

 which I have just pointed out, we may arrive at a knowledge of 

 the age of old exogenous trees in a manner sufficiently accurate 

 for the object of this inquiry. Let us now point out the trees to 

 which it is principally to be directed. The greatest longevity 

 in the vegetable kingdom ought to be found, 1^^, In trees which, 

 by their hardness, incorruptibility, or size, should most power- 

 fully resist inclement seasons; ^d, In countries which are not 

 exposed to ice, or to other causes which too frequently tend to 

 destroy large plants. 



Among European trees we may mention the following : 

 1 . It is well known that the elm (Ormeaii) attains a great size, 

 although it grows very quick. The individual in which I have ob- 

 served the greatest increase, is near Morges. A note of its layers 



