395 



is fixed to the stick transversely, so that when the stick is held 

 vertically the strap is horizontal. The instrument is made as 

 as follows: — A strip of leather two inches wide and three to four feet 

 long is taken, and a drawing-pin or small nail fixed at one end with 

 the point projecting through the leather. The strap is then nailed 

 across a stout stick three and a half feet long, fixing the strap a 

 distance of three feet from the end of the stick, and allowing three 

 inches of that end of the strap which carries the drawing-pin to pro- 

 ject across the stick. The face of the strap next the stick is covered 

 with a strip of white paper, and the apparatus is ready for use. 



To measure a tree stand the stick upright against the tree, 

 girdle the trunk with the leather strap, and measure and at the same 

 time, record, the girth by pricking a small hole in the paper. In this 

 way the strip of paper becomes covered with a number of small 

 pricked holes each of which represents the girth of a tree, taken at 

 three feet from the ground, and the measure of which is the distance 

 of the hole from the pin point when the strap is laid out flat. 



Each tree as measured is chalk marked and at the end of the day 

 the straps are " counted." This is done in this way : the s£rap is 

 laid flat on a table and distances in inches ruled off, measuring from 

 the pin point. The number of pricked holes in each section gives 

 the number of trees of girth corresponding to that section, measured 

 in the day. 



The advantages of this method are that it is very rapid, it does 

 not demand skilled labour in the field as there is no reading of tapes 

 or writing to be done, and above all it gives the daily returns in a 

 suitable form for calculating averages, and the number of trees of 

 each inch or girth, which is valuable information. The disadvantage 

 is that individual trees are not identified. 



In working out the averages two corrections should be applied the 

 first is the addition of half-an-inch to allow for the measurements 

 being taken in even inches, thus 254 trees of girth 26 to 27 inches 

 have the true average of 26^5 inches; the second correction allows 

 for the thickness of the strap and errors in not straining the strap 

 sufficiently tight in measuring. This error is corrected by subtract- 

 ing half-an-inch from the average results. If therefore trees of say 

 26 to 27 inches as measured be called of average 26 inches the two 

 errors will practically cut each other out. Except for very important 

 work it is not necessary to consider these corrections. 



CREOSOTING RUBBER. 



In a lecture given by Dr. Willis at the close of the Rubber 

 Exhibition in Ceylon he raises the question of creosoting rubber. 

 He says u on the whole smoked rubber with creosote turned out 

 better in quality than rubber un smoked. He did not say plain 

 smoking would have much to do with it but there was little doubt 

 that creosote did strengthen the rubber. That raised the question 

 whether they ought to make use of creosote. He thought that it 



