74 



PARA RUBBER. 



knives on the market. It is made in one piece only, which in 

 itself is a great advantage. There are four cutting edges, so 

 that the knife can be used as a push or draw tool for paring 

 right or left. 



The cutting edges are protected from paring a thicker shaving 



than is necessary, at each tapping operation, by a 



guard which is part of the knife and which cannot 



be removed by the operator. 



A modified form of the " Christophe " tapping 



implement (Fig. 10) can be safely recommended, 



Jmore especially for making the V-shaped incisions 

 and the initial incisions in the spiral and herring- 

 bone methods of tapping. This implement is made 

 of metal, and is supplied with three adjustable 

 blades and a movable guide which may be regu- 

 lated to suit the various thicknesses of bark found 

 on different trees, and thus prevent the tapper 

 injuring the cambium tissue. In our experiments 

 with this knife we have found that the guide 

 confused the tappers, and better results were 

 obtained when it was removed. The smallest size 

 blade is preferred, as the larger sizes cut away an 

 unnecessary amount of bark when making the 

 initial incisions, and are rather too clumsy for 

 shaving off thin layers of bark in subsequent 

 operations. 



It is impossible to specify which of the tap- 

 ping implements on the market is the best 

 adapted for tapping operations, in view of the 

 different methods of tapping in vogue, and the 

 FIG. 9. different opinions expressed by planters in re'gard 

 Miller's Patent to the same implement. 



Tapping and One of the cardinal requirements of a good 



ring Knife, tapping knife is simplicity. Elaborate contri- 

 vances for regulating the depth of the incision 

 only confuse the tappers, and, when possible, are removed 

 by them immediately a favourable opportunity occurs. As 

 the depth of the original tappable bark on the trunk varies in 

 different trees from i to ^ inch, it is obvious that a standard 

 depth of cutting blade cannot be adopted ; nor is it likely that 



