GROWTH IN TIIK.'KNESS. 



35 



The higher sectious exhibit not only a regular course, but an entirely similar one, (Voin cross 

 section to cross section. There is no reason to assume that the course at breast liciylif would not 

 follow the same law; therefore there (;an bo (constructed a curve for this height similar to the 

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

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

 tables in the Ai)peiidix). This has been done on the diagram in the Ap|)endix, which shows tlie 

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

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

 the uncertain Juvenile stage: 



Diameter, breast hiiih, of White Pine (averages approximated), in incites. 



That these figures may be considerably 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 

 grows 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 .'> inches 

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

 at two hundred years. 



IIETAII. MEA.SIIREMENTS OK ANNUAL GAIN IN tIRCUMFERENCK. 



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

 Nathaniel Morton, of Plymouth, Mass., exhibiting 38 youug 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 1S9S, 197 

 square inches; the growth 60 scjuare 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 gain in circumference of White Pine trees in Massachusetts. 



Number uf tree. 



1 

 2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 

 10 

 11 

 12 

 13 

 14 

 15 

 16 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 



Number of tree. 



27. 



28 . 



29 . 



30 . 



31 . 



32 . 



33 . 

 34. 

 35 . 

 36. 

 37. 



Total , 



Total in inches. 



Percentage of 

 ^ain aa com- 

 pared with 

 gain of 1891... 



Average gain 

 per tree (in 

 inches) 



Circum- 

 ference 

 in 1890. 



Inchei. 

 314 

 47 

 42 

 404 

 57 

 44i 

 424 

 iU 

 464 

 444 

 47 

 364 



Gain, in quarter inches. 



Total 

 in sis 



1891 1892 1893 1894 1895 1896 yeara. 



4 

 2 



103 



25| 



100 



139 I 190 

 343 ■»7i 



135 



,% i \n 



45J 39)1 12 



176 I 152 , 163 



m m 



Hi 



38 

 38 

 29 

 30 

 20 

 30 



•is 



27 

 28 

 20 

 "9 

 23 



181 157 168 938 



2344 



