Tin- load npiiii llii> beam w.i- '_-i.idu:illy increased until it amounted 

 i" _7. 17(1 \l*. I'ndor this load tin' beam failed \iy shearing longitndi 

 nalU alon- ;i season cniek, iis shown in Ki'_'. Ill, with a partial 

 tension IV-ieimv near tli" rn.l . it tli,. Infill. The season crack fur a 

 diaUnoa of bmt8 It. from tlie centre of tin- beam appear* weatlc p-l 

 through the entire thick new of the beam. 



l'i.'\ ionslv, liiiwrviT, tn this longitudinal shear, the beam had ' \ i 

 dently faileil by tin 1 enppliie.: of the unit 'rial, Fig. 1 I I. mi (In emu 



prossion side along a liin- ii":ir the centre of tin- beam where the liiiilnT 

 was apparently five from kimts and wh- -re lln- lii>re> were parallel with 

 the ;ixis. 



Tin 1 maximum i-kin stress corresponding ID tin- Inail of J7,47(l Ibs. 



i- ."i7H:i 11,^. |HT >'|U,iri' inch. 



The co-efficient of elasticity, a.s deieniiini'il by an increment in tlic 

 defection of ,575-lbs. between tin- lna.U of L'IMHI ainl 12,000 Ibs.. i> 

 1,31 6,900 Ibs. 



Table U shows tin 1 .-rvr.il readings. 



The weij;ht of the beam 0:1 Man-h 10th was L'117 His. 1 (,/., or 27 .''<< 

 Ibs. per cubie fnot, anil its weight on May 2i]'l u.i- L'.")^ ibs. 6 OZS., or 

 26.47 Ibs. ]ier enbie Umi. slhiwin;: a loss ut weight while in the labora- 

 tory at the rate of .OHiS Ib. per cubic foot per day. 



Beam LIX was tested June 2nd, 1 >04, with I lie annular ritiL 

 in Fig. 115. 



i 



* 



a 't 



4- te<too. 



'60 SO. 



fig i IT 



The load was gradually increased uuiil it amounted to 21,700 Ib.-. 

 when the beam failed by the teaniKr njnit of the fibres on tlic tcn>iou 

 ride. 



The maximum skin stress corresponding to this load is 29fi3 Ibs. 

 per M|iiare inch. 



The niaxiuiuin compression at the centre was .7-in., so that tak- 

 ing 14.3 ins. as the effective depth, the maximum eonipressive skin 

 stress is 3079 Ibs. per square inch, the corresponding tensile skin 

 stress being 3396 Ibs. per square inch. 



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

 effective depth, then the maximum skin stress is 32G1 Ibs. per sq. iu. 



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

 deflection of .43-in. between the loads of 2000 Ibs. and 10,000 Ibr,., is 

 905,601 Ibs. 



Table U shows the several readings. 



The weight of the beam on June 1st was 445 Ibs. 13 ozs., or 30.12 

 Ibs. per cubic foot. Its weight on June 8th was 440 Ibs , or 29.72 Ibs. 

 per cubic foot, showing a loss of weight at the rate of .0571-lb. per 

 cubic foot per day. 



Beams LX and XLJ are two old spruce stringers sent to the 

 laboratory by Mr. P. A. Peterson. 



They had been in use in Culvert E 39 on the north division of the 

 South Eastern Railway, 1 miles north of Waterloo Station, since Oct , 

 1891. or tor about three years. 



These timbers were cut and sawn at Keene & Company's mills at 

 the boundary east of Megantic. 



Beam LX was tested on Nov. 10th, 1894, with the annular rings 

 as in Fig. 116. 



The upper portion of the stringer, i.e., the part in tension, was par. 

 tially rotten to a depth of about 1-in., and the effective depth at the 

 centre of the beam did not exceed 11J ins. The remainder of the sec- 

 tion at the centre was in a perfectly sound and good condition. 



The load upon the beam was gradually increased until it amounted 



35 



