270 THE STRENGTH AND ELASTICITY OF IRONBARK TIMBER 
The compound beam is thus seen to be about 3:5 times as 
as one of the two single beams of which it is composed. 
The following table shows the deflections and loads prodi 
them, when the two beams were bolted together without 
transomes (see fig. 9) :— 
W. Central Deflection Central Defiection 
z | w = O or 28, bolts tight. w = 28, slack bolts. 
tb. 
100 0°04 0:07 
200 0-10 0-16 4 
300 0-16 0°24 a 
400 0°23 0°30 a 
500 0°28 0°38 
600 0°34 044 
700 0°41 0°50 
800 0°46 0°56 
900 0°52 | 0°62 
1,000 0°59 
“ 0-66 
allowed to remain throughout the experiment. As the deflection 
of the beam increased the ends a a, fig. 7, were driven tightly 
beam gradually broke down with 2,100 Ib. applied in the centre, 
deflections and loads producing them are given in th 
following table :— 
op ot fo 
Central 
W. Deflection. Ww. | Women | W. pole 
Lee 
Tb. inches. Tb. inches. tb. inches. 
100 0°06 800 0-46 1,500 0-92 
200 0°12 900 0-52 1,600 1°00 
300 0°16 1,000 0°59 1,700 1°07 
400 0°22 1,100 0°66 1,800 117 
500 0:26 1,200 0°72 1,900 1°26 
600 0°32 1,300 0-78 2,000 1°34 
700 0°39 1,400 0°86 2,100 i 
i ie heel 
Another compound beam was then built and tested, with tw? 
concentrated weights each 5 ft. from the centre of beam, so that 
the distance between two weights was 10 ft. The beam broke 
down with a total load of 3,200 Ib., or 1,600 Ib. at each point 
The seven distributed and central loads is found in the 
