SELECTION AND PREPARATION. 13 



SELECTION AND PREPARATION OF THE WOOD. 



The wood was taken from material on hand at the Forest Products 

 Laboratory, and was selected to reveal variations in the specific 

 heat of oven-dry wood due to three causes : (a) Position of the wood 

 in the bole of the tree; (&) locality and site where grown; (c) species. 

 The native species were botanically identified; of the four foreign 

 species, two came with the names given. The species are as follows : 



White pine Pinus strobiLS L. 



Longleaf pine Pinus palustris Mill. 



Red spruce Picea rubens Sargent. 



Western hemlock Tsuga heterophylla (Raf .) Sargent. 



Douglas fir Pseudotsuga taxifolia (Lam.) Britt. 



Red cedar Juniperus mrginiana L . 



Mockernut hickory Hicoria alba (L.) Britt. 



Quaking aspen Populus tremuloides Michx. 



Beech Fagus atropunicea (Marsh.) Sudworth. 



Chestnut Castanea dentata (Marsh.) Borkh. 



White oak Quercus alba L. 



Red oak Quercus rubra L. 



White elm Ulmus americana L. 



Sugar maple Acer saccharum Marsh. 



Black gum Nyssa sylvatica Marsh. 



White ash Fraxinus americana L. 



Unknown wood, foreign, very light. 



Mai champah from Siam. Michelia. 



Unknown wood, foreign, heavier than water. 



Cocobola negra from Costa Rica. Lecythis costaricensis Pittier. 



The 16 indigenous species were chosen to include various forms 

 of nonporous, ring-porous, and diffuse-porous woods. Their density 

 varied from that of white pine to that of hickory. The four foreign 

 woods were selected on account of their high or low density. 



The great majority of the native woods were taken from short logs 

 from the bole of the tree, usually from somewhere near breasthigh. 

 Cylinders were cut in such a way' that their axes ran with the 

 grain of the wood and were turned on a lathe. Each cylinder was 

 about 17 millimeters in diameter and 3 to 9 centimeters long, the 

 length depending upon the weight, which was preferably about 6 

 grams. Each cylinder was marked with an Arabic numeral to indi- 

 cate the species and the log from which it was taken and also with a 

 capital letter to distinguish it from other cylinders cut from the 

 same piece. 



To learn the variation due to the position of the wood within the 

 bole of the tree and to the locality and site where the wood was 

 grown a single species was selected. Douglas fir was chosen because 

 of its wide range both geographically and ecologically and because of 

 the great difference in quality shown by wood of this species from 

 different localities. Sticks collected by members of the Forest 



