29 



(3) Tliat larse beams are stiffer in prnpoitioii to tlieir size than the small beams. In other 

 words, the modulus of elasticity as (letermiiied iiom a large beam is greater than that determined 

 from a 4 inch square beam from the same log. 



Cantion: It must beljorne in mind that the number of tests on large sticks here ottered in 

 evidence is too small to base much of an argument upon; also that, as shown by the log dia- 

 grams in Table IV, the 4 inch l)cams were taken from nearer the sapwood than the large sticks, 

 and this alone may fully explain all the ditterences found. 



MODULUS OF ELASTICITY 



STRENGTH IN LBS. PER SU. IN. 



Fig. ni.— Variatidn of" strength with (list.ince from tho .uroniid. L(iii;j;-lfal' 

 pine {I'iiiiis jinluslris). 



VAKIATION IN STRENGTH ACROSS THE SECTION OF THE LOG. 



In Fig. 15 are shown the jilotted mean results of tests on ditt'eient portions of the cross-section 

 of a bottom log. These results are from one log only, but many other similar studies show sim 

 ilar relations, so that for any full-grown tree the butt-log, at least, will show similar variation. 

 The general law is that the outer rings of annual growth are the weakest portions of the log, readily 



