132 On the Strength, Durability, and Value 
tween the spurs of the roots through which they have access ; 
and in these cases destruction goes steadily on from the 
centre upwards and outwards until a mere shell of the trunk 
is left standing. Trees are sometimes felled partially affected, 
and good sound timber is obtained from the untouched parts : 
in other cases, small perforations are found at intervals 
throughout a considerable length of the tree—this is termed 
“‘snecky timber’ in the ship-yards, and never used for im- 
portant purposes. Many of the insects leave earthy deposits 
in their borings, to which the decayed heart of the tree assi- 
milates ; so that it is not uncommon to find the centre of trees 
filled with fine mould before their fall, which crumbles and 
disintegrates with the concussion. This of course refers to 
aged trees. 
The Swamp Gum grows to the largest size of any of this 
family in Van Diemen’s Land. Its growth is nearly twice 
as rapid as that of the Blue Gum: the annular layers are 
sometimes very large; but the bark, and the whole tree in- 
deed, is so like the Blue Gum, as not to be easily distin- 
guished from it in outward appearance. The leaves, though 
of the same form in the Swamp Gum, are, however, much 
smaller and thinner, and the bark not much more than a third 
of the thickness of that of the Blue Gum. It grows best in 
moist places, which may probably have given rise to its 
name, Some extraordinary dimensions have been recorded 
of trees of this species. I lately measured an appa- 
rently sound one, and found it 21 feet in circumference at 
8 feet from the ground, and 87 feet to the first branches. 
Another was 184 feet in circumference at 10 feet from the 
sround, and 213 feet to the highest branch, or extreme top. 
A third reached the height of 251 feet to the highest branch : 
but I am told that these are pigmies compared to the giants 
of even the Blue Gum species found in the southern districts. 
