554 



THE POPULAR SCIENCE MONTHLY. 



CORRESPONDENCE. 



THE AGE OF TREES. 

 Messrs. Editors : 



HAVING been a regular reader of " The 

 Popular Science Monthly " from its 

 commencement, I have, of course, noticed 

 the various articles having reference to the 

 value of the concentric rings in determin- 

 ing the age of trees which from time to 

 time have appeared in its columns, the last 

 of which, in your August issue, induces me 

 to give you the result of my observations 

 upon this subject. I have had my atten- 

 tion directed to it during a residence of over 

 forty years in Florida, during which my 

 views as to the value of the rings in deter- 

 mining the age of trees have undergone a 

 change. For the first few years my efforts 

 were directed toward securing a grateful 

 shade for the streets of the city of Jackson- 

 ville, and for this purpose the water-oak was 

 selected on account of its beauty, symme- 

 try of form, and rapid growth. And now 

 the appellation of " Forest City," applied to 

 it by visitors, is in no sense inappropriate, 

 for many of the older trees have attained 

 a size which in the State of New York, 

 whence I came, would have required a hun- 

 dred years to reach. Strangers from the 

 North are apt to overestimate the age of 

 our trees, and the number of rings pre- 

 sented appears to confirm in many instances 

 the correctness of their estimate. When 

 first called upon to account for the discrep- 

 ancy shown by the rings, and the known 

 age of the tree, I was perplexed and at a 

 loss to find a satisfactory solution of the 

 problem. But, having from my first arrival 

 here kept a careful record of the weather, 

 an analysis of my tables, a comparison with 

 the record made by Nature on her infallible 

 tablets in the trees furnished me the key 

 to it. 



Here, as well as at the North, the cold 

 of winter puts a stop to vegetable growth, 

 and in all exogenous trees a concentric 

 ring will be formed, embracing all woody 

 matter deposited since the preceding stop 

 to its growth ; but here in this climate causes 

 are in operation that frequently produce as 

 complete a stop to vegetable growth as docs 

 the cold of winter. 



Our spring begins in February, when 

 growth commences a new deposit between 

 the bark and wood, but often (not always) 

 there comes so severe a drought during late 

 spring and early summer as to produce as 

 full and complete a stop to vegetable growth 

 as does the cold of winter ; immediately 

 after comes on our rainy season, generally 



about the middle or last of June, producing 

 a rapid and luxuriant growth, which con- 

 tinues until winter again puts a stop to it. 

 Our rainy seasons, however, do not consist 

 of deluges of rain that overflood the country, 

 but of daily showers, occurring in the early 

 part of the afternoon, lasting an hour or 

 two, leaving the sky bright and clear, the 

 air cool for the rest of the twenty-four 

 hours, comfortable to man, and favorable 

 to luxuriant vegetable growth. The rainy 

 seasons, when regular, continue day after 

 day, for about sixty days, but often there 

 is an interval of clear, sunshiny weather, 

 for about a fortnight, between the rainy 

 periods, which carries the rainy season into 

 the fall months. Upon examination of 

 the tree, it will be found that, when those 

 severe droughts have put a stop to vegetable 

 growth, a concentric ring well defined has 

 been produced, and the growth which has 

 occurred during the rainy season and until 

 winter's cold has formed another and per- 

 haps a thicker ring, making two rings in 

 one year. But the phenomena of such a year 

 are not necessarily repeated each year, for 

 considerable variation occurs. 



What physiological meaning is attached 

 to these rings ? They simply mark the 

 amount of growth of woody matter depos- 

 ited day by day between the periods when 

 a stop to vegetable growth has prevented 

 daily deposit and produced a line of demar- 

 kation, whether from drought of summer or 

 cold of winter. 



For some two or three years before his 

 lamented death, Professor Jeffries Wyman 

 was exploring the mounds of Florida. It 

 was my privilege to enjoy his acquaint- 

 ance and learn his views on matters of sci- 

 ence in which wc were both interested. 

 I have heard him express his belief that 

 he had reached an approximate age of 

 some of the mounds w r hich he had explored, 

 by the indications which the trees growing 

 upon them had furnished. It so happened 

 that we were one time walking down-town 

 together and passed a lot where prepara- 

 tions for building a dwelling-house were 

 going on, and a tree which stood upon the 

 proposed site was being cut down. He re- 

 marked that it was sacrilege to cut down 

 so noble a tree ; he would have changed 

 the site of the house and let the tree re- 

 main as a shade, "for," said he, "it would 

 take a hundred years to produce such an- 

 other tree." In "that, I told him, he was 

 mistaken, as I knew the age of that tree, 

 and it was not yet thirty years old. " Impos- 



