222 A coNfniBtmcKS- TO, Etc. 



age of trees which have sprung up since the foundation of the 

 colony, would afford data for making an approximate guess 

 at the rate of growth amongst some species of Eucalypti 



Instead of forming any opinion exclusively from the concen- 

 tric circles, it appears to me more judicious to ascertain the 

 space of time required for a tree to attain the diameter of afoot, 

 and then to calculate by the rule of proportion, the number of 

 years it would take to increase to any given size. If, for instance, 

 in some of the quickly-growing species, the diameter of the tree 

 should be found to measure a foot in twenty years, then the same 

 tree would require four hundred jears to attain a diameter of 

 twenty feet, which is seven feet less than one measured by Mr. 

 G. Eobinson in the back ranges of Berwick. Or, again, if, in 

 fcome of the very hard and slowly growing species, 50 years 

 should be required for the diameter of a foot, 300 years would be 

 necessary to produce even the diameter of six feet. No rule 

 could be laid down for the species generally, because they differ 

 so much in their grain and specific gravity, but it appears to me 

 that in places where trees have sprung up since the bush was 

 cleared in the early days of the colony, some data are afforded 

 for calculation as to the probable ages of our gum trees. The 

 " iron-bark" I regard as growing very slowly, and therefore I 

 think that even a tree of three feet in diameter may be nearly 

 two hundred years old; whilst of a "bloodwood tree," the wood 

 of which is soft and rapid of growth, the age is considerably less. 

 Trees, it must be borne in mind, have their youth, their prime, 

 and their old age ; and, although we may form some idea of their 

 age so long as they continue to grow, there is great obscurity in 

 making any estimate of the period they may endure after they 

 have passed the time of their perfect development. Since the 

 early days of the colony, when the bush in the neighbourhood of 

 Parramatta was cleared, many " grey gum-trees," &c., have 

 sprung up, varying from one to two feet in diameter, from which 

 I infer that they arc less rapid in growth than the " bloodwood." 

 A neighbour of mine who has had much experience in colonial 

 woods, is of opinion that the " blackbut," and especially the 

 "blue gum," when growing on alluvial soil near the water, 

 increase with more rapidity than the bloodwood, measuring 

 between two and three feet in diameter in the course of thirty 



