An interesting observation on the relation of the age of Gum trees in Tasmania to the number of concentric circles in their trunks is recorded in the Journal and Proceedings of the Royal Society of New South Wales. It is given on the authority of the Rev. J. E. Tenison-Woods, in an article on the forests of Tasmania; and the information was obtained from a Mr. Hill, proprietor of an extensive sawmill at Honey wood, whom Mr. Woods designates as a perfectly reliable authority. This gentleman had observed that the gum trees shed their bark twice annually; and having heard at a lecture on the growth of trees that a ring of wood was added each year, he was induced to test the truth of this statement. There was a Blue Gum tree in his garden at Hobart Town, the age of which he knew with certainty, as his brother planted it eighteen years previously. He felled it and counted the rings, and found them to be thirty-six in number, or two for each year.

As many of the Blue Gum trees first planted in California are now being cut down, and their exact ages known, we should be very glad if some correspondents will send us accounts of the number of rings they find. It may serve to. throw some light on the disputed ages of the big trees.