form may be pointed out ; if what I said re the formation of latex 
with regard to the transpiration of trees be correct, it would be 
interesting to see whether the judicious cropping off of some of the 
leaves will have any effect on the amount of latex. — I am, etc. 
ISOPRENE, 
(In Times of Ceylon.) 
Colombo, August 31 st. 
P.S . — Just as I think of posting this letter, I see a para, in your 
paper re the formation of rubber by polymerisation from a precursor. 
The comparison of what I suggest and what Professor DUNSTAN 
says is at least interesting. 
TAPPING OP PARA RUBBER TREES ON 
PENANG HILL. 
The following results of certain tappings of Para-rubber trees in 
the old Experimental Garden on Penang Hill at an elevation of 
2,000 feet may be of interest, as no trees at this altitude appear to 
exist elsewhere in the Colony. 
The Garden has been abandoned but on my learning of the exis- 
tence of the trees, I gave instructions that some should be tapped. 
The experiments were entirely carried out by Mohd. Hanif, the 
Overseer of the Botanic Gardens, who has had some experience of 
the work. 
Owing to the decision to close the Garden the land has become 
considerably overgrown with small jungle trees, shrubs and ferns, and 
the trees have had no special care for some time past. There are 
about 14 trees on the land planted from 30 to 40 feet apart and 4 
were selected near the road to Government Hill. Their age is about 
12 years and they stand on a slope about 50°. 
The Overseer adopted the herring-bone method and made the 
incisions about 2 feet above the ground. The centre groove was 2 
feet long and the side grooves, 3 on each side, 6 inches long 
In the first 3 trees, two sets of incisions were made and in the 
4th tree 3 sets, carpenter's chisel being used tor the purpose. The 
tappings were made on alternate days, 14 in all, between July nth 
and August 6th, about 8 or 9 a. m. 
The rubber obtained was thoroughly dried and weighed on the 
15th September, the results being shown in Table A. 
The girth of the trees is shown in Table B. The average Minimum 
temperature in the shade during the period of the experiments was 
65-9° and the average Maximum 78° while the average Maximum 
in the sun was 124 0 , 
