45 



Average ultimate breaking unit stresses in pounds per square inch recommended by the 



committee on ''strength of bridge and trestle timbers" American Association of Railway 

 Superintendents of Bridges and Buildings, fifth annual convention, New Orleans, Octo- 

 ber, 1895. 



Kind of timber. 



White oak 



White pine 



Southern, longleaf, or Georgia 

 yellow pine 



Douglas, Oregon, and Wash- 

 ington fir or pine: 



Yellow fir 



Red fir 



Northern or shortleaf yellow 

 pine 



Red pine 



Norway pine ■ 



Canadian (Ottawa) white pine 



Canadian (Ontario) red pine.. 



Spruce and Eastern fir 



Hemlock 



Cypress 



Cedar 



Chestnut 



California redwood 



California spruce 



Tension. 



With 

 grain. 



10, 000 

 7,000 



12,000 



12,000 

 10, 000 



9, 000 

 9, 000 

 8,000 

 10,000 

 10,000 

 8,000 

 6,000 

 6,000 

 8, 000 



|.M)(III 



7,000 



Across 

 grain. 



2, 000 

 500 



600 



500 

 500 



500 



Compression. 



Transverse rup- 

 ture. 



With grain. 



End 

 bear- 

 ing. 



Col- 

 umns 

 under 

 15diam- 



I'tcrs. 



7,000 

 5,500 



8,000 



8,000 



6,000 

 6, 000 

 6,000 



6, 000 



6,000 

 6,000 



4,500 

 3, 500 



5,000 



6,000 



4,000 

 4,000 

 4,000 

 5, 000 

 5,000 

 4,000 

 1,000 

 4.000 

 4,000 

 5,000 

 4,000 

 4,000 



Across 

 grain. 



2, 000 

 • 800 



1,400 



1,200 



,000 

 800 

 800 



700 

 600 

 TOO 

 700 

 ill 10 

 800 



Ex- 

 treme 

 fiber 



stress. 



6, 000 

 4,000 



7,000 



6, 500 

 5, 000 



6, 000 

 5,000 

 4,000 



5, 000 

 4,000 

 3, 500 

 5, 000 

 5, 000 

 5,000 

 4,500 

 5, 000 



Modulus 

 of elas- 

 ticity. 



1,100,000 

 1,100,000 



1,700,000 



1,400,000 



Shearing. 



1,200,000 

 1,200,000 

 1,200,000 



With 

 grain. 



800 

 400 



600 



600 



400 



1,400,000 



1,200,000 

 900, 000 

 900,000 

 7110,000 



1,000,000 

 700,000 



1,200,000 



350 

 400 

 400 



3.".ll 



600 

 400 



Across 

 grain. 



4,000 

 2,000 



5, 000 



4, 000 



3,000 

 2, 500 



1,500 

 1,500 



Note —These and the following tables are printed here as part of the preceding report. In doing 

 so the Forestry Division disclaims anv apparent indorsement of the data contained therein, except as 

 far as its own results are recorded; the other data having been probably obtained from a small number 

 of tests without reference to and allowance for the conditions of the material as to state of seasoning, 

 etc., believed to be an essential requisite. B. E. F. 



