THE AGE OF TREES. 55 



longer possible to count. This instance may be taken to illustrate 

 how unsatisfactory this mode of reckoning really is for all but trees 

 of comparatively youthful age. 



The external girth measurement is for these reasons the best we can 

 have, being especially applicable where the date of a tree's introduc- 

 tion into a country or of its planting is definitely fixed, since it ena- 

 bles us to argue from the individual specimen or from a number of 

 specimens, not with certainty, but within certain limits of variability, 

 to the rate of growth of that tree as a species. In these measurements 

 of trees of a century or more in age, such as are given abundantly in 

 Loudon's "Arboretum," lies our best guide, though even then the 

 growth in subsequent ages must remain matter of conjecture. The 

 difficulty is to reduce this conjectural quantity to the limits of proba- 

 bility ; for, given the ascertained growth of the first century, how 

 shall we estimate the diminished growth of later centuries? The 

 best way would seem to be to take the ascertained growth of the first 

 century, and then to make, say, the third of it the average growth of 

 every century. Thus, if we were to take twelve feet as the ascer- 

 tained growth of an oak in its first century, four feet would be its con- 

 stant average rate, and we might conjecture that an oak of forty feet 

 was about a thousand years old. But clearly it might be much less ; 

 for the reason for taking the third is not so much that it is a more 

 probable average than the half, as that it is obviously less likely to 

 err on the side of excess of rapidity. 



The cypress affords an instance where the approximate certainty 

 of its introduction into England enables us to form some conclusions 

 with regard to its attainable age. The fact of its being first men- 

 tioned in Turner's " Names of Herbs," published in 1548, makes it 

 probable that it was not introduced into England before the begin- 

 ning of that century. But, at all events, the cypress at Fulham, which 

 in 1793 was two feet five inches at three feet from the ground, can not 

 have been planted there before 1674, the year that Compton, the 

 great introducer of foreign trees into England in the seventeenth cen- 

 tury, became Bishop of London. That gives a growth of about two 

 feet in the first century ; but sometimes it attains a higher rate, as in 

 the case of the cypress planted by Michael Angelo at Chartreux, 

 which was thirteen feet round in 1817, giving the average rate of over 

 four feet in the first three centuries. Now, the cypress at Somma, 

 between Lake Maggiore and Milan, for whose sake Napoleon bent the 

 road out of the straight line, is not more than twenty-three feet in 

 girth, so that the tradition which makes its planting coeval with 

 Christianity would seem doubtful ; though if we take three feet as the 

 first century's growth, and take the third as the average, it may evi- 

 dently have been standing in the time of Caesar, as an old chronicle of 

 Milan is averred to attest. 



The Lebanon cedar first planted at Lambeth in 1683 was only seven 



