8o TRANSACTIONS OF ROYAL SCOTTISH ARBOR ICULTURAL SOCIETY. 



Another gauge might be constructed on the same lines for 

 use in woods where there is a fair proportion of sleeper trees 

 with a diameter exceeding 17-18 inches, and where the forester 

 may find it desirable to separate the sleeper trees into two or 

 three classes. In practice, however, it is not a very difficult 

 matter to classify woods of this kind with Gauge No. i, relying 

 merely on an ocular inspection of the trees for the subdivision 

 of the sleeper-sized timber. 



In classifying, with the help of these gauges, timber which is 

 to be exposed for sale, it is necessary to note that in marking 

 any particular lot of timber, one gauge only should be used 

 throughout the process. If there are two lots of timber to be 

 dealt with, the one containing sleeper-sized timber and the other, 

 perhaps on the adjoining area, chiefly timber of spar or pit-wood 

 size. No. I gauge may be used for the former and No. 2 gauge 

 for the area with the smaller timber, but the two lots should be 

 indicated separately in the advertisement. 



The reason for this will be evident when it is observed that 

 a tree marked, say, as 5-inch pit-wood with No. 2 gauge may 

 differ somewhat in diameter from a tree marked 5-inch pitwood 

 with the No. 3 gauge. The principle underlying the use of the 

 gauges is not primarily to have the trees classified according to 

 their diameter at any particular height, but to separate the 

 timber into four or five classes with diameters differing from 

 each other by 2-3 inches. This is, of course, a method 

 generally approved of in scientific works on the mensuration 

 of timber. 



When the marking of the timber has been accomplished in 

 this manner, it will be found that the trees have been very 

 uniformly graded, and the total contents of the stand can be 

 found by determining the contents of the average tree in each 

 group or class, and multiplying this by the number of trees in 

 the group, and adding together the total contents of each of the 

 groups or classes. 



The most accurate method of determining the average tree 

 in any particular group would be to recalliper all the stems in 

 that group at breast-height, adding the basal areas of the 

 individual stems (which can be readily obtained from tables 

 showing the areas of circles which correspond to particular 

 diameters) together in order to get the total basal area of all 

 the trees in the group or class. The total basal area can then 



