1885.] TREE GROWTH. 163 



Mr. Furnas found the annual growth of twenty different varieties 

 of young timber planted by himself, and measured during a period 

 of twenty-five years, to be very irregular ; sometimes small, at 

 others scarcely perceptible, and again quite large. This he attri- 

 butes to irregular conditions. Some seasons are propitious, and 

 others the contrary, as was indicated by the si2e of the concentric 

 rings, especially in young trees. As trees increased in age, the 

 inner rings decreased in size to almost entire disappearance or 

 obliteration, at least to the naked eye. Diminished rate of growth, 

 after a certain age, was found to be the rule. So much for 

 observations made in South-Easteru Nebraska. 



In recent investigations of Thomas Meehan, made during his 

 tour in California and Alaska, and laid before the Botanical Section 

 of the Academy of Natural Science of Philadelphia, he says : — " In 

 order to ascertain whether more than one annual circle of wood is 

 formed in each year, we tested the matter in various ways. For instance, 

 a pine or spruce would be found to make an average growth of a foot 

 a year up to 15 years old ; from that on, 6 inches ; after that, a stage 

 was reached where the erect growth ceased to any considerable extent, 

 and the growth force seemed turned towards the lateral branches. 

 In the pine forests of the Pacific coast there was no danger of error 

 in fixing the age of the average tree of 60 feet high at about 50 

 years. Whenever such a tree was cut down, and an opportunity 

 afforded to count the circles, they would be found to correspond so 

 nearly with the calculated age as to prove that it was quite safe to 

 assume a single circle for a single year. Then there was a remark- 

 able degree of uniformity in the diameter of these annual growths in 

 most trees, so that when once we had the number of circular lines 

 to an inch, and the diameter of the tree, we could tell its age near 

 enough for general purposes. In some pine trees growing on very 

 lich soil we have found as few as about 4 circles to an inch. For 

 instance, a section of a Pinus Lamhertiana in Mariposa, 4 feet across, 

 had but 189 circles ; but here the increased size of the trees corre- 

 spond with the larger annual circles. Trees of this species of pine 

 here measuring 30, and a few 33, feet round, were not uncommon. 

 No matter, however, how vigorous may be the growth of trees under 

 5 or over 100 years, they decrease with age, and we may safely 

 allow 6 rings to an inch in these older sugar trees, which would 

 make the 33-foot tree 396 years old. The outer growths of Sequoia 

 were very narrow ; we counted as many as 18 to the inch, while the 

 rings in the interior of cross-sections would show about 6 to the 

 inch. Allowing 12 as the average per annum, a tree of 33 feet 

 diameter would give 2376 years old, which is about the same as 

 given by an actual count of the rings. 



