[8] 



the above trees, .3745 of an incb, is nearly three-eighths of 

 an inch, or .3750. 



If we had similar and sufficient data from various places, 

 we might make a pretty accurate approximation and gen- 

 eralization of the kind above illustrated; in this, the data 

 being limited, the region to which they apply must also be 

 limited, and to the species — the single species only — ^as 

 above given. 



The pines are quick-growing trees, and, in common with 

 other related forest forms, make a proportionately larger 

 growth in their early years, or, in other words, make thicker 

 annual rings when young than when old, though in an 

 equally vigorous condition, so that a measurement of young- 

 trees, though useful as showing how long we may have to 

 wait to get a profitable return in fuel or lumber from an 

 artificial plantation; such young trees would not answer the 

 purpose of a standard of age or measurement fnr the large 

 trees of natural forests. 



Ill the neighborhood of Berkeley, trees of the Monterey 

 pine, nine to ten years of age, show a maximum diameter 

 of one foot three inches, being a growth of over an inch a 

 year, and a mean diameter, so far as I have measured, of 

 nine! inches, the result of several trees. These were planted 

 for ornamental purposes. 



Sections of the following species of forest trees, indigen- 

 ous lO the Pacific Coast, are contained in the Museum of 

 the [University of California, and yield the data given 

 beloW: 



Ahes grandi^ or white fir — Larger diameter, 23 5-16 

 inches; smaller diameter, 22 11-16 inches; mean diameter, 

 23 inches ; thickness of bark, three-fourths of an inch ; 

 annual rings, 146; mean annual growth, .1575 of an inch, 

 or a Httle under one-sixth of an inch per annum. 



Abies Z>ouglassii, or Tsuga Douglassii, the hemlock spruce, 

 so called — Larger diameter, 17 J inches; smaller diameter, 



