56 PARA RUBBER. 



the cuts deeper than the previous ones ; this is effected by holding 

 the knife at the proper angle. Leaning the knife over to the right 

 makes the cut deeper, while leaning over to the left makes it less 

 deep. The knife is constructed to prevent the cooly cutting deep 

 enough to touch the cambium. 



The basal cutting surface of this knife has now been made much 

 narrower, the change effecting a greater economy as less material 

 s likely to be removed during each operation. 



No. 3 consists of a spur-like arrangement, which is provided 

 with a number of sharp cutting teeth. It is used to cut the latex 

 tubes near the cambium or to tap the milk vessels which have 

 become unduly distended with latex. 



The latest patterns are provided with one or two pieces of metal, 

 the solid margins of which prevent the teeth from penetrating too 

 deeply ; these can be changed in order to allow the teeth to penetrate 

 the cortex to the necessary depth — a wise provision when tapping 

 trees of widely different ages. It can be used alternately with No.2 

 knife, though in the Peradeniya experiments the spur knife is used 

 at least twice as often as knife No. 2. It is by the use of these knives 

 that the yield of 12 lb. of rubber was obtained in 6 months from an 

 eleven-year-old tree in the south of Ceylon, and 4 lb. in two months 

 from each of four trees at Peradeniya. The knives have elicited 

 the admiration of many rubber planters who have adopted the prick- 

 ing and paring method. The value of a pricking instrument does 

 not appear to be fully appreciated by many, but when it is pointed 

 out that by means of such an implement the excised area in three 

 months' work, tapping twice per week, is less than one inch, its 

 usefulness cannot be doubted. 



Dixon's Knife. 



This consists of a grooved open knife blade, which can be ad- 

 justed to cut the bark to any depth or at any angle. The cutting 

 part can be easily removed from the handle of the knife and is there- 

 fore capable of being replaced when worn out. The base is pro- 

 vided with a pricker for determining bark thicknesses, removing 

 scrap rubber from the cuts and making holes for attaching tins, &c. 

 It can be used for making the original groove or for paring the lower 

 surfaces in any direction, the excision being made by drawing the 

 knife towards the operator. 



In a later pattern the cutting blade is provided with sharp 

 margins, two blades, detachable and adjustable, to be used according 

 to particular requirements. By favour of Mr. Dixon the accom- 

 panying illustration on Plate 10, Series A, is here reproduced. 



Macadam'< Com p. Prickek. 



A specimen of a pricking instrument has just been received from 

 Mr. Macadam of Culloden estate, Kalutara, which is worthy of a 

 detailed description as it is constructed on a sound principle and is 



