RUBBER 647 



and a half times that from the second, and four times 

 that from the highest. 



At the present day only one cut, or at most two, is 

 used. Two cuts yield about 40 per cent, more than one 

 cut. The ultimate advantage of the one or the two cuts 

 remains to be proved. It is not decided whether the 

 yield from, say, the lowest 3 ft. is less by tapping with 

 two cuts than by tapping first with a single cut and, 

 after the lower part of the tree has been finished all round, 

 continuing with another single cut at 3 ft. The time 

 required in the second case would be greater, while the 

 difference in the yield is doubtful. But these are subjects 

 for future experiments. 



Tapping Intervals. 



Probably no other point has been the subject of so 

 much discussion as the question of tapping intervals. A 

 tapping interval is the time which elapses between succes- 

 sive tappings. That would appear clear enough, but the 

 discussions show that it is not, and it is necessary to 

 add that "a tapping" is the process of extraction of 

 latex by cutting, whether it is performed on the same 

 side of the tree as the last or on the opposite side. Each 

 time the coolie cuts the tree is a tapping; if he taps one 

 side of the tree on Monday and the other side on Tuesday, 

 and so on, that is daily tapping on alternate sides. 



In the second place, an experiment which sets out to 

 show the difference in yield with different tapping in- 

 tervals must be conducted on the same plan throughout. 

 It is useless to alter the number of cuts as well as the 

 tapping interval and then make deductions as to the effect 

 of the latter. Most experiments on tapping intervals 

 are vitiated by the introduction of other factors. 



Given a straight experiment, i.e., the same method of 

 tapping, same number of cuts, same angle, and same 

 fraction of circumference throughout, one clear result 

 emerges, viz., that the longer the interval the greater 

 the yield per tapping, up to an interval of about seven 

 days. This, of course, refers only to tappings on the 

 same side, not tappings on alternate sides. There are, 



