TRANSVERSE TESTS OF JARRAH. Cl. 
TRANSVERSE TESTS or JARRAH MabE aT SYDNEY 
THCHNICAL COLLEGE. 
By JAMES NANGLE, F.I.A. 
[With Plates XXIII.—XXV.] 
[Read before the Engineering Section of the Royal Society of N. 8. Wales, 
September 19, 1906. | 
TABLES No. I. and Il. contain results of transverse tests 
made on twenty pieces of West Australian Jarrah. The 
test pieces were approximately 2 inches by 2 inches in cross 
section, and all but two were 24 inches long. They were 
tested for moduli of rupture and elasticity on a span—in 
all cases but two—of 22 inches, in the 50,000 pounds Olsen 
testing machine at the Sydney Technical College. A piece 
of wood about 23 inches long was placed under the centre 
bearing piece of the machine, on top of each specimen. 
Deflections were taken at every 200 pounds of load by 
means of a deflectometer. ‘This deflectometer consists of 
a straight edge which bears on pins, in the neutral plane 
of specimen, over each bearing. Attached to the straight 
edge isa magnifying arm or pointer. The short arm of the 
pointer is attached to a pin in the specimen; the end of 
the other arm indicates, to an enlarged degree, the deflec- 
tion on a scale which is attached to one end of the straight 
edge. The advantage of the apparatus is that the error 
due to crushing at bearings is eliminated from the deflec- 
tion readings, since the latter are taken, not from the bed 
of the testing machine, but from the neutral plane of the 
specimen. The load taken for the calculation of the 
modulus of elasticity was about one-fifth of the breaking 
load. 
