STEENGTH OF MATERIALS. 29 



Woods. 



Ash, toughest 1000 lbs. 



Beech .^. 718 " 



Box 1250 " 



Cedar 712 " 



Chestnut 656 " 



Elm 837 " 



Locust 1280 " 



Maple 656 " 



Oak, white 718 " 



Pine, white 550 " 



" pitch 750 " 



Poplar 437 " 



Walnut.. 487 " 



jHetals. 



Steel, best 9370 lbs. 



" soft 7500 " 



Iron, wire 6440 " 



" best bar 4690 " 



" common bar,. 3750 " 



" inferior bar 1880 " 



" cast 1150 to 3100 " 



Copper, wire 3800 " 



" cast 2030 " 



Brass 2800 " 



Platina wire 3300 " 



Silver, cast 2500 " 



Gold, cast 1250 " 



Tin 310 



Zinc, cast 160 " 



" sheet 1000 " 



Lead, cast 55 " 



" milled 207 " 



From these tables we may ascertain the strength of 

 chains, rods, etc., when made of different metals, and of 

 timbers, bars, levers, swing-trees, and farm implements, 

 when made of woods. Wood which will bear a very- 

 heavy weight for a minute or two, will break with two- 

 thirds of the weight when left upon it for a long time. 

 This explains the reason that store-house and barn timbers 

 sometimes give way under heavy loads of grain, which 

 have appeared at first to stand with firmness. 



