122 On the Strength, Durability, and Value 
measured upon a scale attached to the wood by a silk thread 
stretched over the frame-work by plummets, in the same 
manner as described by Professor Barlow. The weights 
(56 lbs. and under) were obtained by permission from the 
Public Stores: they were placed upon a scale hung upon 
the middle of the wood by means of a, half-inch iron eye, 
24 inches square. 
The weights were placed upon the scale until the deflection 
amounted to $ an inch, when they were removed, and the 
wood was permitted to resume its original straight form : the 
weights were then replaced, and removed at each succeeding 
4 of an inch of deflection, until the wood was observed to 
lose, however slightly, the power to recover its rectilineal 
form ; a failure in this respect, amounting to the diameter 
of the thread, was sufficient to determine its character for 
elasticity,—after which the weights were continued until the 
fracture took place. The elasticity and strength of the Blue 
Gum exceed, generally, those of all woods hitherto tested. 
The apparatus used for ascertaining the direct cohesion 
was of a less complicated and expensive kind than that 
described in the Essay alluded to. Lengths of about 16 
inches were cut from the pieces broken transversely, and 
turned in an ordinary lathe to about 14 inches diameter : 
about an inch in the middle was farther turned down to 
2 inch diameter, which was then carefully squared to 4 of 
an inch with a fine file; and this in each case formed the 
portion to be tested. Through a hole accurately bored 
across the thick part of these pieces, near each end, short 
bolts were passed : to these bolts were attached short pieces of 
good rope, having eyes spliced in each end to receive them. 
A second piece of rope, passed through the first in the form 
of a link, sustained the scale at the lower end ; and a similar 
one at the upper end hooked the beam which held the whole. 
