338 AUSTRALIAN NATIVE PLANTS. 
Some of these points will be dwelt upon below, and the author 
will now content himself by adding that one of the greatest diffi- 
culties in the utilization of results is the doubt which exists as to 
the identity of the timbers experimented upon by different 
observers. A wood may be stated to be ‘‘Ironbark” or ‘ Blue 
Gum,” and it may be one of some half a dozen timbers. In 
regard to Eucalyptus timbers in particular, the author can say 
(as one through whose hands many hundreds of specimens of 
such timbers have passed, and who has some little know- 
ledge of Australian timber trees) that the origin of those used 
in many experiments is open to doubt,* and that in regard to 
many species the work of testing the timber, having previously 
placed its identity beyond all doubt, by means of a complete series 
of botanical specimens obtained from the same, or an adjacent 
tree, remains to be done. 
Following are references to published experiments on the 
strength of Australian timber :— | 
1851. ‘On the strength, durability, and value of the timber 
of the Blue Gum} of Tasmania, and of some other Eucalypts { 
for ship-building.” With tables, by James Mitchell. (Papers and 
Procs., Royal Society of Van Diemen’s Land, Vol. ii., Part i., 
1852. 12th Nov., 1851.) 
“ The apparatus used for testing the transverse strength con- 
sists of two strong pieces of frame-work, seven feet asunder, 
attached to the sides of a small building. The deflection was 
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 (56lbs. and 
under) were placed upon a scale hung upon the middle of the 
wood by means of a half-inch iron-eye, two and a half inches square. 
“The weights were then placed upon the scale until the 
deflection amounted to half an inch, when they were removed, 
and the wood was permitted to resume its original straight form; 
* With the reservations made when speaking of some individual specimens of 
timber, the origin of the timbers experimented upon in the instances selected by the author 
is open to no doubt. 
+ E. globulus, 
t E. viminalis aud E, obliqua, 
