*t* ". ot-t 



60 S-,-j. /. 



Tlif in;,, I nidii die K.-aiii was gradually incrca.scd until it amounted 



to IT.OfiO His., when tlio beam tailed by the crippling of the 6bre on 



'iipreinn face, V\x<. lid, lil. The load was still increased until 



under 19,14011is. the beam again laildl by the tearing apart of the 



tilir, s mi the i nsion face. 



The maximum .-kin stress OOrreSf onding to the load under which 

 ciippling took place is <>752 lli>. per square inch. 



Thf total compression of the beam undrr a loud of 17,050 Ibs. was 

 .-1 in., so that taking the clf-etive dtptli to be 11.01 ins., the corre- 

 sponding maximum skin c< impressive stress would bo 6886 Ibs. per 

 square inch, the corresponding skin tensile sirc.-s being 7193 Ibs. per 

 square iucb. 



Assuming the usual law to hold good for the whole of the effective 

 depth, the maximum .-kin stress would be 70f)0 Ibs. per square inch. 



The co-efficient of elasticity, ;is determined by an increase in the 

 deflection of 1.435 in betw.rn the loads of 21)00 and 12,000 Ibs., is 

 1,786,000 Ibs. ; it is 1,858.400 Ibs., as determined by an increment 

 in the deflection of .8l-in. between the loads 3500 and 9500 Ibs., and 

 is 1,681,10(1 H,s., as determined by an increment in the deflection of 

 1.135 in. between the loads of 2000 and 10,000 Ibs 



'fable K shows the several readings. 



The test occupied 26 minutes. 



The weight of the beam on March 10th was 379 Ibs. 10 ozs., or 

 44.20 Ibs. per cubic foot ; upon April 20th, the date of test, ihc weight 

 was 322 His. 8 ozs., or 37.55 Ibs. per culi. ft., showing a loss of weight 

 at the rate of .1622-lb. per cubic foot per day. 



Beam XXIX. This beam was cut from the heart of the tree, and 

 was tested March i:>th, 1894, with the annular rings as in Fig. 62 



/g62 



inn 



ftft 



The load upon the beam, was gradually increased until it amounted 

 to 11,960 Ibs.. when the beam faikd ly the crippling of the fibres on 

 the compression face, r'i-s (13, 04. The lead was still further gra- 

 dually increased (o 12,4(jd His , when the beam was completely frac- 

 tured l>\ the' tariii'j apirt of the tilnes in i|,e tension face. 

 . The maximum skii; .-trr.-s ec rrespii tiding to the breaking lead of 

 11,960 Ibs. is 4S18 \\. per M,n:,re inch. 



The total compression of the timber at the centre was .1 5-iu., so that 

 taking ll.l-in. as the effective depth, the maximum skin compressive 

 -IP N would be 4SS.'i 1K-. per .-i|iiare inch, the corresponding skiu teu- 

 siie .-ire.-- living ")IJ1G Ibs. per square inch. 



A. uming the usual law to hold good for the whole of the effective 

 depth, the maximum skin stre-- wmild be 4949 Ibs. per square inch. 



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

 >!' iii. in tli>- deflection between the leads of 1000 and 000011 



21 



