APPENDIX. 



METHODS, 



TESTING. 



The 6-foot props were tested in compression parallel to the grain 

 at a speed of 0.119 inch per minute. A bearing block was used 

 between the prop and the base of the machine. The compression of 

 the prop, as indicated by the movement of the head of the testing 

 machine, was read to thousandths of an inch by means of an Olsen 

 deflectometer. Figure 6 shows a prop in the testing machine after 

 failure. 



The 8-foot caps were tested on a 7-foot span with third-point load- 

 ing. The tests were made on a 200,000-pound Riehle testing machine 

 at a speed of 0.231 inch per minute. The ends were supported by 

 curved cast-iron bearing blocks and the load applied at two points 

 (one-third the length of the span from either end) through curved 

 wooden blocks. Deflections were read at the center of the beam to 

 hundredths of an inch by observing on a taut string the movement 

 of a polished metal scale attached to the timber. The method of 

 loading is shown in figure 7, all parts of the testing machine being 

 omitted except the weighing platform. 



The 16-foot lodgepole pine beams were tested on a 15-foot span 

 with third-point loading. The arrangement was similar to that 

 used for the caps. 



MOISTURE DETERMINATIONS. 



A 1-inch section was cut from near the point of failure of each 

 piece tested. This was immediately weighed and later dried to con- 

 stant weight at the temperature of boiling water. The loss in weight 

 divided by the dry weight, expressed in per cent, is the moisture 

 content of the piece. 



GENERAL OBSERVATIONS. 



The length, weight, and diameters of the timbers were obtained 

 j ust before testing. The rings per inch and the proportion of sap wood 

 and of summerwood were obtained from a section cut near the point 

 of failure. The values for the amount of summerwood are approxi- 

 mate, as the summerwood bands were not distinctly marked in many 

 of the pieces. 



COMPUTATIONS. 



The load and deflection at the elastic limit were obtained from the 

 load-deflection curve, and at maximum load by direct observation. 



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