18 



H. T. BOVEY ON THE STEENGTII OF DOUGLAS FIE, ETC. 



Red Pine. 



Comparing the timbers Douglas tir, white pine and red pine, it may be inferred, as a 

 result of the experiments, that the strength of Douglas tir to resist transverse loading, 

 shearing and compressive forces is greater than the strength either of red pine or white pine. 



An examination of the tables giving the results of the experiments on direct tension 

 would seem to indicate that the ultimate tensile strength of red pine is greater than that of 

 either Douglas fir or white pine. Red pine is certainly much stronger under tension tliiin 

 under compression, and this is indicated by the transverse experiments, which show that 

 under transverse loading the beams invariably fiiil by crippling on the compression side. 



In conclusion, a few experiments have been made on Douglas fir and white pine string- 

 ers which have been in use for some years, and so far it has been found that Douglas fir 

 retains its strength more completely than white pine. The only doubtful characteristic 

 to which it seems advisable to call attention is the tendency of Douglas fir to split longi- 

 tudinally without any apparent external cause. 



I desire to acknowledge the assistance given to me in carrying out these investigations 

 by Messrs. C. B. Smith, J. Gr. Kerry, and by Mr. Withycombe. 



