Section III., 1894. 



[ n ] 



Trans. Roy. Soc. Canada. 



II. — On the Strength of Doujhis Fir, White Pine and Red Pine} 



By rrofessor H.'^.^IBovey, LL.D. 



(Read May 23, 1894.) 



In this paper it is proposed to ^ive a record of certain results relating to the strength 

 of Douglas fir, white pine and red pine, three of the most important of the Canadian tim- 

 bers of commerce. The experiments were conducted in the testing laboratories of McGill 

 University, and were made with the Wicksteed 100-ton machine, by means of an arrange- 

 ment specially designed for the purpose. 



The centre of each beam, as is shown by the diagram, bears upon a hardwood block 



resting upon an iron saddle directly suspended by means of four steel rods from the lever 



of the machine. The frames at the end of the beam are two hydraulic presses, which 



may be adjusted at any recpiired distance from the centre of the beam up to about 12 feet, 



thus rendering it possible to test the strength of beams 24 feet in length. The pressure is 



conveyed to the cylinders of the presses by means of pipes with flexible joints, wliich lead 



to the top of the pressas, from an accumulator capable of giving a i)ressure of more than 



3000 lbs. per square inch. 



The operator stands near the centre of the beam and admits the fluid by means of 



specially designed valves, which enable him to regulate the pressure easily and very 



1 This paper must be read in connection with the following paper in this section by Professor Penballow on 

 " Some Structural Variations in certain Canadian Coniferse." 



