490 KANSAS CITY REVIEW OF SCIENCE. 



ANNUAL GROWTH OF TREES. 



A. L. CHILD, M. D, 



Are the concentric rings of a tree a reliable record of its age in years ? Sucb 

 has been the conception — in fact, the undisputed knowledge-Aof the world, for 

 all time past. T have no recollection of ever having seen or heard the authority 

 of this record disputed till Desire Charnay, in his " Ruins of Central America," 

 said, when speaking of the age of the ruins as proved by such a record : "Un- 

 fortunately for the argument, it is altogether fallacious and proves nothing. I 

 have put the evidence to a test. On examining a slice of wood of a shrub that I 

 knew as a fact was only eighteen months old, I found that it had eighteen con- 

 centric rings. I thought it was an anomaly, but, in order to convince myself I 

 experimented upon trees of all kinds and sizes, and invariably found the like result 

 produced in very nearly like proportions."^ 



M. Charnay' s statement was, in my estimation, rather loose, and lacking ia 

 "'the proof of his absolute knowledge of the age of the trees examined; and again, 

 so far as applicable to the case, was only so in a tropical climate, where the con- 

 ditions were entirely different from those surrounding us in a higher latitude, and 

 altogether raised but little doubt on the subject. 



In April of 1871 I planted a quantity of the seed of the common red maple 

 {Acer rubrum). In transplanting, in 1873, they were placed too near each other, 

 and it has become necessary to cut a part of them out. While cutting, I noticed 

 that the concentric rings were very distinct, and it reminded me of M. Charnay's 

 statement. I took sections from the butt-end of each tree (four of them) and 

 dressed the ends off at an angle of some 35° with the line of the body, thus 

 largely increasing the exposure of each ring, and then counted them. 



The situation, exposure, and condition of these four trees were, so far as I 

 could see, identical. I had personal and positive knowledge that they had each 

 twelve years' growth upon them, and I could count on each of the different sec- 

 tions from thirty-five to forty concentric rings. True> I could select twelve more 

 distinct ones between which fainter and narrower, or sub-rings, appeared. Nine 

 of these apparently annual rings on one section were peculiarly .distinct, much 

 more so than any of the sub-rings ; yet, of the remaining, it was difficult to decide 

 which were annual and which were not. 



The thickness of these annual rings varied from two and one-half millimetres 

 to twenty-eight. This measure, of course, gave more than double the real thick- 

 ness ; but was preferable to a right-angled measure, as it gave better facilities for 

 exactness, and yet preserved the proportion between the several rings unchanged. 



Now, to ascertain what relation or connection there might be between the 

 meteorology of the several seasons and the growth made during the same, I se- 



1 " North American Review," September, 1881, p. 401. 



