As-lulling the usual law to hold good for the whole <>f the effective 

 depth, the maximum skin stress would be 7,382 Ibs. per square inch. 



The co-efficient of elasticity, as deduced by an increase in the deflec- 

 tion of .39 in. betweeen the loads of 2,000 Ibs. and 20,000 Ibs., it 

 1,639,500 His., while it is 1,691,620 Ibs. for an increment in the 

 deflection of .42 in. between the loads 2,000 Ibs. and 22,<><lO Ibs. 



Table H gives the readings under the several loads. 



The weight of the beam on the day of test was 33.75 Ibs. per cubic- 

 foot, and the total weight on Oct. 3rd was 438 lb=. 7 ozs. 



Beam XXIII from Trestle No. 789 was tested Nov. 28th, 1893. 

 with the annular rings as in Fig. 44, and showing the heart in one of 

 the faces. 



ITS to. 



The load upon the beam was gradually increased until it amounted 

 to 47,560 Ibs., when the beam failed by the tearing apart of 

 the fibres on the tension face, which was immediately followed by a 

 longitudinal shear, as in Figs 45. 46. 



The n.aximuin skin stre.-s corresponding to the load of 47.560 Ibs. 

 is 7339 Ibs. 



The co-efficient of elasticity, as deduced from an increment of 

 .66 in. in the deflection between the loads of 2,000 Ibs. and 22,01)1) H>v 

 is 1,878,950 Ibs. 



Table I shows the readings under the various loads. 



The total weight of the beam on Oct. 3rd was 654 Ibs. 12 ozs., <>i 

 38.95 Ibs. per cubic foot; the total weight on Nov. 28th, the date of 

 test, was 549 Ibs. 8^- oz?., nr 38.59 Ibs. per cubic foot, showing a loss of 

 weight in the laboratory at the rate of .00643 Ibs. per cubic foot per 

 day. Estimating the weight of this beam from a solid block cut out 

 of the beam, it was found to be 39.13 Ibs. per cubic foot, or .54 lb. 

 per cubic loot heavier than the weight deduced from the total weight 

 of the wh'de beam. 



Beam XXLV from Trestle No. .'J5. This beam was tested Nov. 

 25th, ISSK-5, with the annular rings as in Fig. 47. It contained tw 

 vertical -in. tolt holes about half way between the centre and ends, and 

 a few knots of average size appeared on the lace, ft also container 

 several season cracks. 



The initial load, including the w.-inht of the beam, was 5,000 Ibs., 

 and the load was gradually increased up to 41,000 Ibs., when t he- 

 material ut one end of the beam was crushed in. The ends of the beam 

 were found to bo very much the worse for wear and in a rotten condi- 

 tion. Releasing the beam from load the ends were sawn off and the 

 beam was replaced at 9-ft. centres, when the load was gradually in- 

 creased until it amounted to 76,900 Ibs. Under this load the beam 

 failed by longitudinal sheiir, which was accompanied by a certain 

 amount of cripi ling of die fibnscn i he compression side of thecentie, 

 a.- in Figs. 48, 49. lii 



