[4] 



16f inches; mean diameter, 17J inches; thickness of bark, 

 half an inch; annual rings, 96; mean annual growth, a trifle 

 under .18, or something over one-sixth of an inch. 



Abies Mertensiana — Larger diameter, 18 J inches; smaller 

 diameter, 16f inches; mean diameter, 17J inches; thick- 

 ness of bark, a trifle over half an inch; annual rings, 110; 

 mean annual growth, nearly .160, being something less 

 than one-sixth of an inch per annum. 



These three species of Abies are represented in the above 

 measurement by trees which grew in or near Gualala, Men- 

 docino county, an exceptionably favorable station so far as 

 moisture is concerned, the country being well watered, and 

 the county, in common with the entire region from the 

 Oregon line to and inclusive of Marin county as the south- 

 ern terminus, being part of a meteorological province, which 

 receives not only a greater average rainfall than other parts 

 of the State, but also the fullest advantage of the summer 

 fogs which, borne shoreward by the trade-winds, are con- 

 densed by the lofty evergreens which here abound and fall 

 to the ground, dripping through the foliage of the trees, 

 like a gentle shower. A comparison of so moist a region 

 with the drier areas, shows at a glance the necessity of a 

 careful consideration of environmental conditions in con- 

 nection with deductions from data, of the kind herein 

 referred to. 



A section of t^^equoia semper vir ens ^ our common redwood, 

 shows, counting from the circumference toward the center, 

 a growth of three inches in 95 years, or, more particularly, 

 95 growth rings averaging .0316 of an inch per annum. 

 Notwithstanding the majestic proportions which the Se- 

 quoias attain, the above measurement, as well as an- exam- 

 ination of the ends of a large number of redwood boards, 

 show that these trees are of slow growth. 



The measurements of a specimen of Sequoia gigantea, as 

 given with great particularity by Professor Whitney in the 



