424 MR ANGUS R. FULTON ON EXPERIMENTS TO SHOW 
magnifying lever. ‘Thus any deflection taking place at the centre of the beam B is 
magnified in the ratio = (8 in this particular apparatus). The scales E are so graded 
that the actual deflection is at once read off. With this arrangement any error due 
to crushing of the timber by the knife-edges is eliminated, the actual deflection of the 
neutral axis is obtained, and by the use of two scales placed one on either side of the 
beam, both being read and the mean taken, any inequality of pressure due to want of 
alignment between timber and testing machine is counteracted. 
The deflections were measured with the beam resting first on its radial face and 
then on its tangential, and the formula by which the modulus was determined was 
Oak. 
Greatest dimension tangential :— 
ieee ; tial 
A.—Beam resting on Radial Face. mmc Oe aE: 
Face. E, 
No S.G . S E, 
‘i A 
Span. | Breadth.| Depth. Ey. || Breadth.| Depth. | Hg. 
11 ‘T4 36 1°56 3 | 520 3 1°56 523 1:005 
12 215 5 1°6 3 | 568 3 1:6 615 1:085 
Crore le 13 (5) “1 1°6 3°03 616 3:03 16 650 1:06 
23 72, 3 1-44 3°06 528 3°06 144 561 1:065 
31 Jif) Bs 1:62 2°95 585 2°95 1°62 603 1:035 
34 ‘73 Fe 1:61 2:97 578 2-97 1:61 596 1:03 
Mean 1:047 
Greatest dimension radial :— 
uw uv | y u 
14 If) 36 3 16 582 16 3 610 1:05 
Group II. 91 oes 7 3°05 1:6 599 1:6 3°05 Lye) ‘96 
33 2 . 3:06 16 643 | 16 3:06 637 “99 
33 HD) a 3°06 1:44 583 1-44 3°06 553 95 
Mean 99 
From Group I. it would appear as though position B possessed greater stiffness 
compared with A, but Group II. shows a slight advantage in the other direction. A 
modification, however, ought to be made in B of Group I. and A of Group IJ. on account 
of the beams in these cases being comparatively broad and shallow, and therefore 
possessing a greater degree of stiffness. Allowing for this, in both cases the advantage 
may be said to lie with the beam resting on its tangential face—to the extent, however, 
of only 2 or 3 per cent. Other Oak experiments bear this out, though, where knots 
or decided flaws obviously affect the results, they have been left out. 
The following were some of the results obtained with Ash and Box :— 
