1,210,100 Ibs. The co-effisient of elasticity, as deduced from an in- 

 crement of 1.31 5-in in the deflection batween the loads of 1000 Ibs. and 

 7000 Ibs., is 1,187,000 Ibs. 



Table L shews the several readings. 



The test occupied 27 minutes. 



The total weight of the beam was 290 Ibs., or 32.89 Ibs. per cubic 

 foot on March 10th, and 282 ibs. 6 ozs., or 32.03 Ibs. per cubic foot 

 on March 13th, showing a loss of weight in the laboratory at the rate 

 of ,2866-lb. per cubic foot psr day. 



I 



,o**a** f*f ""*. *tcnttrt-*f*f **' 



/-/ 66. fig* 7 



Beam XXX. .Tnis beam was te4ed May 3rd, 1894, with the 

 annular rings, as in Fig. 65. VVli3ii the baam was placed in position , 

 it showed an upward camber of 24 ins. 



The load upon the b 3:1111 was gradually increasid until it amounted 

 to 5700 Ibs., when the beam failed by the crippling of the fibres on the 

 compression face, Fig. 66, the crippling extending 2J ins. upwards 

 from the skin. The load was still increased, and when it amounted to 

 f>580 Ibs., the beam broke right across the tension face about 2 inches 

 from the middle of the beam, and vertically above the second line of 

 crippling on the compression side, Fig. 67. 



The maximum skin stress corresponding to the breaking load of 

 5700 Ibs. is 4634 Ibs. per square inch, and the maximum skin stress 

 corresponding to the load of 6580 Ibs. is 5340 Ibs. per square inch. 



The co-efficient of elasticity is 1,322,000 Ibs., as determined by an 

 increment in the deflection of 1.69-in. between the loads of 1000 and 

 5000 Ibs.; it is 1,329,900 Ibs., as deduced from an increment in the 

 deflection of .84-in. between tho loads of 2000 and 4000 Ibs. 



Table L shows the several readings. 



The weight of this beam on May 4th, the day after the test, was 150 

 Ibs. 11 ozs., or 30.96 Ibs. per cubic foot. 



Beam XXXI. Tliis beam was tested May 4th, 1894. It was cut 

 from the heart of the tree, and the annular rings were situated as in 

 Fig. 68. Season cracks ran intermittently from end to end of the beam 



1 



in die neighbourhood of the neutral plane, the cracks extending radially 

 outwards from the heart. Tho beam was free from knots for a distance 

 of 7 inches on one side and 1 inch on the other, and the grain ran 

 parallel to the axis. 



The load upon the beam was gradually increased until it amounted 

 to 6500 Ibs., when it failed by a crippling of the fibres on the com- 

 pression face, Fig. 69. The crippling occurred exactly at the centre 

 and extended 1.5in. upwards from the skin. The load was then 

 continued, and, when it amounted to 7900 Ibs., the beam failed by the 

 tearing apart of the fibres on the tension face, Figs. 70, 71, and a line 

 of crippling on the compression side timber opened upwards for a 

 distance of about 2 ins. or 3 ins. The fracture on the tension 

 side took place about 5J ins. from the centre, and the timber opened 



22 



