VOL. IV. L896. TRAMS, OAR. Boo G I. 



TIM'. SI RENG 111 OF 



CANADIAN DOUGLAS FIR, 

 RED PINE, WHITE PINE AND SPRUCE. 



Hv HENKY T. HOVEY, M.lNsi.C.K., LL.D. 

 (Beatl January 25, 1 



In tin- pre-ent Paper it is proposed to give a statement of tin- iv.-ulN 

 wliicli hiive been obtained up to the present time, from the numerous 

 experiments which have been carried out in the Testing Laboratories, 

 Mi (i ill University, on the strength of Canadian J>ouglas Fir, Red Pine 

 White Pine and Spruce. 



These experiments, which have now extended over a period of more 

 than two years, will still be continued, and it is hoped th;it the results, 

 will }> re the profession in a Paper on some future occasion. 



In order that the subject may be treated in as comprehensive a 

 manner as possible, the engineers and lumber merchants, who must 

 ,-irily l>e most particularly interested, a iv earnestly requested to give 

 their co-operation. They can render valuable service by sending to 

 the University Laboratories timbers of any and all sizes. These timbers 

 should, in each case, be accompanied by a history giving the treatment 

 of the timber from the time when the tree was felled, as, for example, 

 the locality in which the tree grew should be specified, the manner in 

 which tlic log was brought to the mill, the length of time during which 

 it was kept in water (salt or fresh), the time during which it was kept 

 in the pile at the mill, and, if the timber has already been in service, 

 the length of this service. Any other details respecting the history of 

 the timber may also be given, so that the information may in every 

 ease be as complete as circumstances will permit. 



The attention of members is specially directed to the tables showing 

 the deflection of beams under transverse loading] and also to tables 

 showing the extension of specimens under direct tension. 



These tables tend to prove conclusively the statement made by the 

 author many years ago, i.e., that timber, unlike iron and steel, may be 

 strained to a point near the breaking point without being seriously 

 injured. It will be observed that in almost all cases the increments of 

 deflection and extension, almost up to the point of fracture, are very 

 nearly proportional to the increments of load, and it seems impossible 

 to define a limit of elasticity for timber. This probably accounts for 

 the continued existence of many timber structures in which the timbers 

 have been and are still continually subjected to excessive stresses, the 

 factor of safety being often less than H. Whether it is advis- 

 able so to strain timber is another question, and experiments are still 

 required to show how timber is affected by frequently repeated strains. 



TBANSVEBSE STRE.NUTII. 



The following Table gives in inches the distances between the cen- 

 tres of the end bearings (1), the mean depths (d) and the mean 

 breadths (b) of the Beams I to LXI referred to in this 1'uper : 



Beams I II III IV V VI VII 



1 





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