92 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. lv. 



on one side and flat on the other, and on the flat side is 

 provided with a number of shallow notches, while on the 

 convex side it is graded with millimetres and centimetres so 

 as to serve for measuring the breadth of the riugs. 



This pin is pushed in between the little cylinder of wood 

 and the wall of the borer, with its notched side turned 

 towards the former until the wood is firmly wedged against 

 the borer ; when, on the instrument being reversed through 

 half a turn, the cylinder of wood loses its connection with 

 the tree at the end A of the borer. It is next desirable, 

 though not generally necessary, to rotate the instrument one 

 full turn from left to right, which has the effect of forcing 

 the piece of wood well up into the tube. 



The handle (B, C) is next pulled back so as to become 

 detached from the borer, and as the pin, on account of its 

 large head, cannot pass through the slot, it, along with the 

 cylinder of wood, is withdrawn from the tube, and the first 

 part of the operation, which usually takes about half a 

 minute, is completed. 



As it comes from the tree the little cylinder does not 

 show the rings very distinctly, so it is laid in a small brass 

 trough, and a thin slice is removed by a sharp knife in such 

 a way that the fibres are cut at right angles to their length, 

 which leaves the rings distinctly visil:)le. 



Wlien the borer has been withdrawn from the tree a hole 

 of the diameter of I inch is left, wliich, in the case of 

 dicotyledonous trees, may be closed by a little grafting wax 

 or other antiseptic, but in the case of conifers the resinous 

 exudation makes any dressing unnecessary. 



The practical and scientific uses of tlie instrument are 

 very various, and need here only l)e indicated. The effect 

 upon trees of thinning, pruning, or any other arboricultural 

 or sylvicultural operation, can be ascertained by examining 

 the rate of growth a year or two after the trees have been 

 subjected to the new conditions, and comparing it, upon 

 the same little cylinder, with the growth of the trees before 

 the operation was performed. One tliereby obtains a very 

 decided indication as to whether or not the trees have been 

 Ijenefited by the operation, and whether it should be carried 

 further, or has already l)cen carried too far. 



Similai'ly we can quickly determine Llic annual giitwLli in 



