to 16,050 Ibs., when it failed by tlie tearing apart of the fibres on the 

 tensile side. The load was still increased, and a more complete frac- 

 ture occurred under a" load of 21,240 Ibs. Immediately after this 

 second fracture the jockey weight was run back until the lever again 

 floated, when the load was 15,900 Ibs. The load was again gradually 

 increased until it amounted to 18,800 Ibs., when fracture again 

 occurred. 



The maximum skin stress corresponding to the breakirog load of 

 16,050 Ibs. is 2934 Ibs. 



The maximum compression of the material at the centre was .25-in., 

 so that taking the effective depth to be 11. ins., the maximum coin- 

 pressive s-kin stress is 3043 Ibs. per square inch, and the corresponding 

 tensile skin stress is 3184 Ibs. per square inch. 



If it is assumed that the usual law holds good for tho whole of the 

 effective depth, the maximum skin stress becomes 3118 Ibs. per square 

 inch. 



The co-efficient of elasticity, as determined by an increment in the 

 deflection of ,390-in. between the loads of 2000 and 12,000 Ibs., is 

 1,352,250 Ibs. per square inch. 



Table V gives the several readings. 



The weight of this beam on Nov. 10th, date of test, was 255 Ibs. 

 12J ozs., or 27.26 Ibs. per cubic foot. 



Beam LXI was tested Nov. 17th, 1894, with the annular rings as 

 in Fie. 117. There were season cracks from end to end on the 

 front face and numerous knots of medium and small size on the sides. 

 Tho darkened portion indicates sapwood. 



The load upon the beam was gradually increased until it amounted 

 to 18,400 Ibs., when the beam failed by the tearing apart of the fibres 

 on the tension face. 



The maximum skiu stress corresponding to this load is 4309 Ibs. per 

 sq'iare inch. 



The maximum compression of the material at the centre was .21 

 in., so that taking the effective depth to be 14.29 ins., the maximum 

 skin comprcssive stress is 4432 Ibs. per square inch, the corresponding 

 tensile skin stress being 4565 Ibs. per square inch. 



If it is assumed that the usual law holds good for the whole of the 

 effective depth, the maximum skin stress becomes 4502 Ibs. per square 

 inch. 



Tlie co-efficient of elasticity, as determined from an increment of 

 ,6-in. in the deflection between the loads of 1000 Ibs. and 9000 Ibs., 

 is 1,250,850 Ibs. 



The weight of this beam on Nov. 17th, date of test, was 267 Ibs., or 

 28.85 Ibs. per cubic foot. 



The following Table gives a summary of the results obtained for 



Spruce : 



NEW TIMBER. 





OLD TIMBER. 



36 



