GROWTH IN THICKNESS. 



35 



The liigher sectiou.s exhibit not ouly ;i rejjuhir course, but an entirely siuiihir one, f'loni cro.ss 

 section to cross section. There is no reason to assume tliat the course at breast height would not 

 foHow tlie s;inie law: therefore there can be constructed a curve for tliis height similar to the 

 curves of higher sections, using for guide points the data obtained from a series ol measurements 

 made to establish the yield of pine in which trees were measured at breast height (compiled in 

 tables in the Appendix). This has been done on the diagram in the Appendix, which shows the 

 diameter development of ditt'erent cross sections for dominant trees. From this can be read 

 the following average dimensions as approximating the diameters of each decade, leaving out 

 the uncertain juvenile stage: 



Diameter, breast liiyli, of IVhite Pine {averages appruximated), in inches. 



That these figures may be considerablj- exceeded (even by 50 to 60 per cent) under favorable 

 conditions will appear from the various tables of measurements in the Appendix. Especially is 

 this the case in the second-growth groves of pine. 



As will be readily seen in the curves after the juvenile stage, during which the diameter 

 gro-ws very slowly, an acceleration in the rate takes place, which soon reaches a maximum, 

 continuing at that for a short time, and then slowly and persistently declining from about .'3 inches 

 per decade between forty and fifty years to 1^ inches at one hundred years, and half that amount 

 at two hundred years. 



DETAIL MEASIREMENTS OK ANNUAL GAIN IX CIRCUMFERENCE. 



An interesting set of most accurate observations have been made and reported by Mr. 

 Nathaniel Morton, of Plymouth, Mass., exhibiting 38 young trees of White Pine, which had 

 sprung up among oak and other hardwoods, mixed with White Pine and a few Pitch Pine in an 

 old, rather-neglected piece of woods, and which were measured every year from 1891 up to 1898. 

 The trees stand rather open. The age varied from twenty-eight to forty-two years, most trees 

 being between thirty and thirty-six years old and their average age thirty-six years in 1891. 



In 1891 the average cross section .'3 feet from ground was 131 square inches: in 1898, 197 

 square inches; the growth 00 sijuare inches, or about 9 square inches per year, one tree making 

 15 square inches per year. This growth corresponds to a growth in circumference of about 1.3 

 inches per year, or a growth in diameter of four-tenths of an inch per year. 



The detail measurements are given in the following table : 



Table V. — Annual i/ain in circumference of IVhitc Piiif treis in ilassacJiusetts, 



Number of tree. 



1 

 2 

 3 

 4 

 5 

 C 

 7 

 8 

 9 

 10 

 11 

 12 

 13 

 14 

 15 

 16 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 



Number of tree. 



Gain, in quarter inches. 



Total 



Clrcum- 1 



ference in six 



in 1890. 1891 1892 1893 1894 1805 1896 years. 



27. 



28 . 



29 . 



30 . 



31 . 



32 . 



33 . 



Inches. 

 31* 



36. 

 37 . 



47 



42 



404 



57 



44^ 



424 



444 



464 



444 



47 



364 



Total. 



Tutal in inches. 



Percentage of 

 gain as com. 

 pared with 

 gain of 1891... 



Average gain 

 per tree {in 

 iuche») 



103 139 

 25J 34J 



38 

 38 

 29 

 30 

 20 

 30 



190 181 



474 *H 



157 168 , 



394 42 : 



2344 



I 



100 135 184 176 152 163 



M I M I m iii m m 



