TIMBER: ITS STRENGTH, AND HOW TO TEST IT. 9 
One of these sets of round specimens was turned down to such 
a diameter in the centre as to give a tensile cross-sectional area 
of only about ? square inch, and the other set so as to have a 
very much larger cross-sectional area, of about 1? square inches. 
The first series of these round bars had ends so heavy and strong 
that, in order to shear the ends off, a shear area of 134 square 
inches had to be destroyed, while in the second series the ends 
were reduced in size so as to give only about 9g square inches of 
shear area. The results of these two sets of tests are given in 
Tables IT. and III. 
TABLE II. Zenston Tests of Timber. 
Rounp Bars (see Fig. 4). 
Mumbercl | Kind of Wood. Strssar Sh" SESS| atethod of Fracture 
maaan pet adn. fa pears ia 
6780 Ash, : , 6°62 0°37 Sheared at head. 
6781 Beech, . : 6°93 A Tension. 
6782 Birch, |: on a ae Se | Bs 
6783 | Hickory, . : 6°30 | 0°37 | Sheared at head. 
6784 | Mahogany, ; Arg | SOr25" 1?" 99 >» 
6785 Oak, ; ; 2°95 | ap | Tension. 
/ 
TaBLeE III. Zenston Tests of Timber. 
Rounp Bars (see Fig. 4). 
Bamber of | Kind of Wood. Suess a | Shear Stress | Method of Fracture. 
Tons per sq. in. Tons per sq. in. 
6786 Ash, : : 2°22 0°45 Sheared at head. 
6787 Beech; | );. - 2°37 | 0°50 ” » 
6788 Birch, 4 : 2°39 0743 | 9 ” 
6789 Hickory, . : 2°06 0°40 » ” 
6790 Mahogany, . 0°76 | Ov15 Tension inside head. 
6791 Oak, : : 1°92 | 9°40 Sheared at head. 
