CONCENTRIC RINGS OF TREES. 259 



CONCENTKIC KINGS OF TKEES. 



By A. L. CHILD, M. D. 



IN" the December number (1882) of the " Monthly," you published 

 an article prepared by me, on the "Annual Growth of Trees," 

 which has been somewhat largely commented upon, in the periodicals 

 and press of the day, as also by the " American Congress of Forest- 

 ry " at St. Paul. I am glad to note this interest in the subject, as it 

 will cause more accurate observation of the facts in the case. As 

 many of my critics have apparently read only extracts from the arti- 

 cle, and have accordingly drawn very incorrect inferences as to my 

 viewsj I wish to restate some of the more important points, and the 

 evidence sustaining them. 



In June of 1871 I planted a quantity of seed as it ripened and fell 

 from some red-maple trees. In 1873 I transplanted some of the trees 

 from these seeds, placing them on my city lots in Plattsmouth, Ne- 

 braska. In August, 1882, finding them too much crowded, I cut some 

 out, and, the concentric rings being very plain and distinct, I counted 

 them. From the day of planting the seed to the day of cutting the 

 trees was two months over eleven years. 



On one, more distinctly marked (although there was but little 

 difference between them), I counted on one side of the heart forty 

 rings. Other sides were not so distinct ; but in no part were there 

 fewer than thirty-five. There was no guess-work about the age of 

 this tree. A daily record of meteorological events for the Smithso- 

 nian Institution and Signal- Office for over twenty years, and a life-long 

 habit of daily record of all important events, had led to much care 

 and caution in such matters. Hence, from my own record, I knew the 

 tree had but twelve years of growth ; and yet, as counted by myself 

 and many others, it had forty clear concentric rings. 



Here permit me to quote a few lines from the original article, 

 which,, so far as I have seen, have been entirely ignored or overlooked 

 by all commentators : " I could select twelve more distinct ones (rings) 

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

 these apparently annual rings on one section were peculiarly distinct ; 

 much more than the sub-rings. But, of the remaining, it was difficult 

 to decide which were annual and which were not." When first cut, 

 and while the wood was green and the cells filled with sap, these 

 rings were very clear and plain ; but, as the water evaporated and the 

 wood contracted, they showed less plainly. I have a section of it now 

 before me, and I can not make out clearly over twenty-four, where, 

 when green, forty were clearly visible. This section was not at first 

 so distinctly marked as a section forwarded to Professor Cleveland 



