2go 
favourable than in 1902), the variations of the yield were of such a 
manner that we may deduce from the experiments that it is not 
advisable to make long incisions. 
The long incisions also have the disadvantage that they require a 
considerable time to heal. 
In 1901, the question arose whether reopening the incisions, above 
as well as below, did not bring about an increase of the yield. 
To that effect the incisions on one side of each of four trees were 
only reopened on the upper edge and those on the other side on 
both upper and lower edge. The results were as follows : — 
No. of Tree. 
7- 
21. 
22. \ 23. 
,■ 1 
a 
b 
a 
b 
a 
b | a 
b 
Tapped surface Ms. 
Total yield, Grs. 
Yield for Ma., Grs. 
2*33 
380 
163 
2*33 
552 
237 
i*39 
181 
130 
i*39 
37o 
266 
1*77 
236 
133 
i*77 ! 1*645 
403 | 221 
228 ! 134 
1-645 
300 
182 
a . — Only tapped on lower edge. b . — Tapped on both edges. 
The figures shew that the incisions reopened on both upper and 
lower edges and gave more rubber than those where only the lower 
edge was worked. 0 
In the first case, the average yield was 143 grammes per M 3 of 
surface and the other 238 grammes. 
The double working does not, however, give twice the product. 
In 1903, the above experiments were made with a larger number 
of trees. 
The period of tapping was, however, remarkably dry. 
No. of Tree 
» . • 
3 
8c 
9 
25 
26 
« 
27 
28- 
29 
30 
3i 
32 
33 
Surface tapped 
M 3 ... 
2-2 
i*43 
2 ‘ 
1*73 
i*43 
i*55 
i*54 
i*39 
1*65 
i*55 
1*52 
1*75 
Total yield 
Grs. ... 
858 
512 
8lO 
500 
780 
487 
500 
570 
877 
709 
610 
910 
Yield per M 3 
Grs. ... 
390 
358 
j 4 °5 
289 
545 
3i4 
325 
410 
532 
457 
401 
520 
As no notes were taken of the very dry East Monsoon, unhappily 
only one tree (No. 3) on which the incisions were reopened only 
on the lower edge, can be compared with 1 1 others whose incisions 
were reopened on both edges. 
The yield of tree No. 3 amounted to 390 grammes per M2 of 
tapped surface, while as the average of the doubly tapped trees we 
get 414 grammes. 
Albeit a tapping of the upper and lower edge yields more rubber 
than only working the lower edge, the bigger yield does not, how- 
ever, cancel the disadvantages of the incisions becoming too broad 
by a double tapping. They require a considerable time to heal. 
