654 
THE TROPICAL AGRICULTURIST. [April 1, 1903. 
. 7%e t»t*l yield inchiding scrap(I7 ounces) was 77 
ounces heing an average of Vbi ,oimces of dry riibber per 
tree. 
Four yea') old trees.— The four year old trees selected 
tor tapping were all 2 feet or more at 3 feet from the 
base, the mean girth being '26-65 inches, and that of 
the whole of ihe originally planted trees 12'45 inches, 
the largest tree having a girth of 31 inches at a yard 
from the ground. The trees were planted 24' x 24' or 
76 to the acre and 21 trees were selected from two 
acres, representing 14 per cent of the total. As in the 
former case the herring-bone system of tapping was 
adopted and the incisions renewed on 12 alternate 
days. 
The total yield per diem of 21 trees was as follows :— 
Table XVIII. 
Result of tapping 4 year old trees. 
June 1902. 
Weight of dry rubber in Ounces. 
1 8 5 7 9 11 13 16 17 19 21 23 
Total yield 
per Diem 2' 2'6 2-5 3-5 S 5 3-5 3-75 2*75 8 5 3-25 3-75 3. 
Total Yield ) Scrap Total Yield 
per Diem J 9'75 47 25 
Average yield per tree 2'25 ounces. 
These trees whicli are growing under most" favour- 
able conditions, are a perfect picture of health and 
probably equal anything that can be found at this age 
m this part of the woild ; and I doubt whether, even 
in its native habitat, the rate of growth exceeds, or 
indeed equals this, It ia apparent, however, that 
there is very little profit to be made if a tree must be 
tapped on twelve occasions in order to obtain a yield 
of 2i ounces of rubber. 
Seven year old trees.— Ai S'tiawau there art about 
20 trees owned by the natives and, as is usually the 
case with native cultivation, they have been much 
neglected, They are growing on a dry sandy soil, 
which is covered with'Lalang' {Imperata Sp.)a, vigo- 
rous growing grass and although said to be seven years 
old have an average girth of 26-2 inches only, at 8 feet 
from the base, which is but slightly in excess of the 
average girth of the four year old trees, referred to 
above, and even a trifle less than the four yea^r old trees 
selected for tapping. 
These trees were also tapped v;ith herring-bone inci- 
siona but the operation wns more severe than in the 
two previous experiments ; the vertical channel extend- 
ing to a height of 4 ftet, while the oblique incisions 
extended haif way rouiul the trunk, there being four on 
either side the vertical channel at distances of 1 foot 
The incisions were reoewed on 12 ocoitsions at intervals 
of two days, tho yield from ten trees being shown in 
the following Table. 
Tablb XIX. 
Result of tapping 10 trees 7 year old, 12 tappings every 
2nd day. 
Ounces. 
Weight when dry ... ... ... 119-75 
Scrap ... — .. ••• 28 
Total ... 142-75 
Areragfl weight of dry rubber per tr«e, 14-275 ounces. 
The fact that these traes yielded nearly six times the 
amount obtained from four year old trees, of a similar 
girth but growing under more favourable conditions, is 
partly due to the more severe tapping to which they 
were subjected, but only partly, I think, for I am in- 
clined to regard this us sufficient proof that age is 
the most iu^portant factor to be reckoned with 
when couuideiiiiK whether a tree 13 fit to tap or not, 
and that it cannot be argued that booauue a tree 
■ay ten years old, gives 3 pounds of rubber, that halt 
this amount might bo obtained from a tree half 
the age. As inst.aiicing the fact that ft □ annual yield 
is procurable, it may be remarked here, that although 
tapped very severely, these same trees, when tapped 
exactly 12 months later, gave an average return of 
over 9 ounces of dry rubber per tree. On this occasion 
the incisions were much smaller and were renewed 
on eight occasions only ; still the yield exceeds that 
obtained on the fl.i.-.=t eight occasions at the previous 
tapping. 
Eiyht to nine year old trees. — Only five trees were 
available of this age, all of which were tapped on 
a system previously explained, viz , three small 
herring-bone incisions to each tree. These trees vrera 
also native property, but were growing under some- 
what better conditions than the trees just referred to 
having been planted among old coffee trees, whosa 
decayed roots and foliage had provided a small 
amount of Tiumun, a constituent in which this soil waa 
particularly lacking. The mean girth of these treea 
was 39-8 inches or 13-6 inches in excess of the seven- 
year old trees growing close by. 
The total yield dry rubber per day from five trees ii 
shewn in Table XX, 
Table. XX 
EIGHT YEAR OLD TREES. 
Trees 55, 56, 57, 58 and 39. Small herring-bone inci- 
sions (three per tree). 
Tapped on eight consecutive days : — 
1st day 4 ounces dry rubber including scrap. 2nd 
7^, 3cd W^, 4th Hi, 5thl0|, 6th 12}. 7th 13i 8th 131 
Total Weight 83|. Average loeightofdry rubber ptr 
tree 16-75 ounces. 
Considering that the incisions were only renewed on 
eight occasions this may be considered a very grati- 
fying return, being more than twice the amount 
obtained from the seven to eight year old trees when 
tapped on eight occasions, a strong argument in 
favour of good cultivation. It will be rememberd 
however, that the system of tapping was different, and 
as this system has always given the best returns, ths 
comparison may not appear quite a fair one. 
Ten to eleven year old trees. — Tables VII and VIII 
which were given in the chapter relating to the area 
of the trunk to be tapped, shew the yield obtained 
from 10 to 11 year old trees growing under similar 
conditions. When tapped with V incisions and re- 
newed on twelve occasions the average weight per tree 
of dry rubber was '28^ ounces. When tapped with 
small heiriiig-bone incisions, exactly twelve months 
later, and the incisions renewed on eight occasions, 
the yield per tree was 19 1 ounces of dry rubber. 
Here again we have a large increase of yield with 
age, as compared with the 4, 7 and 8 year old trees, 
a very noticeable point in connection with all these 
experiments. These trees gave about ten times the 
yield obtained from the four year old trees, although 
growing under more adverse conditions, and twice 
the amount obtained from the seven year old trees 
with considerably less labour. The yield from other 
10 year old trees will be seen on reference to Tables 
III, lY, V and VI, the aggregate results being 721*25 
ounces of wet rubber obtained from 10 trees being an 
average of 72-12 ounces per tree, or after allowing 
for a loss of 50 per cent on drying 2J pounds per tree. 
The largest amount obtained from a single 10 year 
old tree was 16 i ounces of wet rubber, which when 
thoroughly dry weighed 5 pounds 6i onnoes. Thii 
tree, which does not figure in any of the fore- 
going tables, was 5 feet 3 inches in oircamferenoe, 
and was tapped with herring-bone incisions, renewed 
on 14 alternate days. 
The cost of extraction of the latex depends firstly oa 
the age and dimensions of the tree operated opon, 
secondly, on the instrument used. Assuming that the 
trees tapped are eight years old and of good growth, an 
average of two ounces of dry rubber per day may bo 
relied upon, and with an ordinary pruning knife a 
coolie can easily tap three trees an hour, or 15 trees a 
working day of five hours. The remainder of bia time 
would be partly employed by shaving off the rongh 
bark and getting the trees ready for tapping on the 
following day, collecting the latex and conveying it to 
