until it amounted to 40, 000 Ibs., when the beam failed by the crippling 

 of the fibres on the compression side in the neighbourhood of a small 

 knot 1 \ in. above the compression face, Figs. 34, 35, 36. The crippling 

 extended about 4 ins. above this face. The load was still gradually 

 increased until it amounted to 49,600 Ibs., when the beam again failed 

 by the tearing apart of the fibres on the tension face. 



The maximum skin stress corresponding to the load of 40,000 Ibs., 

 and disregarding the compression of the timber, is 6559 Ibs., and 

 the skin stress corresponding to the load of 49,600 Ibs., is 8127 Ibs. 

 per square inch. 



The total compression of the timber was .345-ins., so that taking the 

 effective depth under this load to be 11.655 ins., the maximum skin com- 

 pressive stress would be 6710 Ibs. per square inch, the corresponding 

 skin tension stress being 7125 Ibs. per squ ire inch. 



Assuming the ordinary law to hold good for the whole of thi- effective 

 depth, the maximum skin stress would be 6936 Ibs per square inch. 



The co-efficient of elasticity, as deduced from a change in the deflec- 

 tion of.22-in. between the loads 4000 Ibs. and 12,000 Ibs., both forwards- 

 and while being relieved from load in the first reading, and also during 

 the second loading, is 1,571,150 Ibs. 



Table G shows the several iv.ulings. 



The weight of this beam when shipped from Vancouver, April 21st. 

 was 349 Ibs, or 41.16 Ibs. per cubic foot ; when delivered at the labora- 

 tory on June 9th, it weighed 329 Ibs., or 36. 70 Ibs. per cubic foot, and 

 on Nov. 3rd it weighed 311 Ibs. 01 o/s., or 34.92 Ibs. per cubic foot, 

 showing a loss of weight between Vancouver and the laboratory at the 

 rate of .091-lb. per cubic foot per day, and a loss while in the labora- 

 tory at the rate of .0121-lb. per cubic foot per day. 



The time occupied by the test was 26 mins. 



Beam XXI. This beam was tested Nov. 3rd, 1894, with the annu- 

 lar rings as in Fig. 37. 



Ftg 3d. 



The load upon the b,.am was gradually increased until it amounted 

 to 6000 Ibs., when it was gradually relieved of load, at the rate of 1000 

 Ibs. for each observation, and the beam returned to its initial condition 

 without showing any sign of set. The load was again gradually increased 

 until it amounted to 17,960 Ibs., when a sharp fracture took place by 

 the tearing apart of the fibres on the tension side, and this was accom- 

 panied by a simultaneous crippling of the fibres on the compression 

 side, Figs. 38, 39, 40. 



The maximum skin stress corresponding to the load of 17, 1)60 II'-. is 

 7787 Ibs. per square inch. 



The total compression of the timber at the centre was .16-iu.. s 

 taking the effective depth at the centre to be 8.82 ins., the maximum 

 skin compressive stress at the point of fracture is 7901 Ibs. per square 

 inch, the corresponding skin tensile stress i>eing 8221 Ibs. per sq. in. 



Assuming the ordinary law to hold goi>d for the whole of the effec- 

 tive depth, the max. skin stress would be 8100 Ibs. per'sq. in. 



The co-efficient of elasticity, as deduced by a change in the deduc- 

 tion of ,48-in. between the loads of 1000-lbs. and 6000 Ibs., durini; the 

 first loading, and while being relieved of load, is 1,588,400 Ibs. 



Table G shows the several readings. 



The weight of this beam when shipped from Vancouver, April 21st, 

 was 164 Ibs., or 38.86 Ibs. per cubic foot ; when received at the labora- 

 tory on June 9th, the weight was 151 Ibs. 4 ozs., on 33.02 Ibs. per cubic 

 foot, and on Nov. 13th, the date of test, the weight was 139 Ibs. 10 



14 



