$62 
THP T^OmOAL AdRieULTURIST. 
[February 2, 1S91. 
the bed of the stream oould be utilized as a further 
supply for Colombo. And, although, by the hel^j of the 
service tank, with a oapaoity of 8,500,000 gallons at 
Colombo, three millions of ga'lons are now supplied 
instead of the two millions originally estimated, it 
seems probable that, looking at the rate at which the 
population is inerea-ing, (2 per cent per annum at 
least,) the duplioati' g of the ex sting 20 inch p pe 
may, ere long, become necessary. It is just 
possible that Negombo, which is now dependent 
on wells at a considerable distance from the 
town, might, in addition to Colombo, be supplied 
from a second pipe? Mr. Burne.t expressed the 
hope that the forest over the catchment area, in 
which there are no abodes save those we have men- 
tioned and no cultivation of the soil, should be pre- 
served in perpetuity. Bat as the larger timber trees 
within the reserve come to maturity, there is no 
reason we can see why they should not be dealt with 
by the Forest Department, the vacancies being 
filled up by planting seedlings or by natural re- 
production. Meantime it would seem that there is 
scope for the planting of handsome and us-ful trees 
round the Lake, outside the grass margin, of course. 
The springing up from the waters, too, of a few of 
our indigenous freshwater fishes, during our visit, 
suggested the idea that here are most favourable 
conditions for breeding the gou<ami of Mauritius, 
the large golden carp of Java, and the best fishes 
of Southern India as described by Mr. Thomas. 
Apart from the economic value of the fish, we 
suppose their prestnce would tend to purify the 
water of the organic matter on which the fishes 
would feed. We need not tell our readers how 
greatly the margin of greensward adds to the beauty 
of the Lake, while the numerous boulders which 
are scattered over the surface of this margin give 
a fresh pieturesquenass to the scene. At one place 
on the shore of the Lake, not far from the re- 
mains of the coconut tope which the elephants made 
short work of wh n the human owners of the 
palms had been removed, there is further evidence of 
former life and action, in the shape of mounds of 
earth thrown out in digging a plumbago pit. The 
construction of the bund was a work of no slight 
difiSculty from the depth which had to be reached 
before solid rock without fissures was found. The 
length of the embankment at the top is 120 
yards ; the length of the foundation trench 160 
yards ; the greatest height of the embank- 
ment 72 feet ; the greatest depth of the 
foundation trench 72 feet, and the greatest height 
from the bottom of the foundation trench to the 
top of the embankment 109 feet. The contrast 
of the bright green of the grass on the long out- 
side slope of the bund and the dark weathered 
appearance of the blocks of gneiss of which the 
facing wall is composed and also the fragments blasted 
out of the spillwater channel, is very striking. 
Equally striking was the eontrist between the 
surrounding expanses of wild jungle and the 
roses, hibiscus plants, bougainvilleas, crotons 
and other shrubs, which Mr. Gibson has suc- 
ceeded in growing around his and his family’s 
ruly solitary abode. The owner of a tea planta- 
ion at least two miles distant talks of the Water 
Works Engineer as his “neighbour, next door.” 
We were glad to find that the family had not 
suffered from fever, the Engineer himself being a 
picture of robust health, notwithstanding the 
performance of duties which involve constant 
exposure to the weather, by night as well as by 
(Jay. — The total oapaoity of the reservoir (176 
acres area, and 360 feet above sea level, or 260 feet 
above the level of the water in the service tank on 
the Bunamit of Maligakanda at Colombo) is no 
less ban 1,373,000,000 of gallons, e<jual to 25i 
inches depth of rain on the' drainage. As 
we have already stated, the Colombo supply is 
drawn at depths below the surface of 12, 24 or .36 
feet, and the capacity to the lowest level of supply 
is 1,233,001,000 gallons, equal to 6,000,000 
gallons for 200 days. It will thus be seen 
that if no serious accident happens to the 
great pipe, against which all possible precautions 
are taken, there is no fear of the oontinuanoe of an 
ample flow of w iter to Colombo. The miin p'pe ia 
25 miles an 1 5s2 yards in Lng h from the straining 
Well at the ou let towers in the Labugama Lake 
to the Maligakande reservoir at Colombo. I now 
again quote some interesting details from Mr. 
Burnett’s report: — 
The top level of Labugama reservoir is 360 ft., and 
the wnter-h-vel in the gauging tank is 102 ft- above sea; 
the fall is therefore 258 ft., giving a h- ad or loss for 
friction of lOJ ft. per mde. The pipe thus delivers 
3 000,000 gallons in 24 hours as measured into the 
Service reservoir. 
The leve' of the pipe where it leaves the straining 
tanks at Labugama is 303J ft. above sea. In three 
miles from Labngama it falls 233| ft. to the level of 70 
feet. In three miles fnrth-r it falls to the level of 30 
feet, and crosses the Hanwella flat, 19 miles from 
Colombo, at the height of only 20 to 25 ft. above sea 
level. For 16 miles out of the remaining length the 
level of the pipe varies from 5, 10, anil 15 to 20 and 25 
feet above sea level, rising at intervals for short dis- 
tances to 39, 60, and 70 ft. For 19 miles the pipe is 
thus subject t > a preasnre of 300 to 355 ft., or abont 130 
to 150 ib. per square inch when a valve is closed. Great 
care is iherefore required in working the valves to pre- 
ventshock on the pipe, which wonld lead to certain bre tk- 
age, and special valves are placed every half mile or so 
for this purpose, so that every halt mile length can be 
i.solated for repairs when required — even then, special 
care and training is necessary to avoid danger in dealing 
with the heavy pressure on the long length ol pipe. 
The extremely flat contour of the section for long 
lengths required special arrangements in creating arti- 
ficial aummi's for the escape ot the air disengaged from 
the water in motion, with the necessary air escape 
valves, in order to prevent the flow of water being 
reduced or stopped from the pipe becoming charged with 
air. The.se air valves are often rt quire I in duplicate, 
and are placed from one-eighth to one-fourth mile apart 
where artificial summits were made, and on every natural 
summit along the line of section. Cleansing valves 
have been placed at every depression or hollow for 
scouring and emptying the pipe. Altogether there are 
on the main pipe 48 special stop valves, 20 in. dia- 
meter ; 44 special stop valves, 8 in. diameter ; 61 clean- 
sing valves, 6 in. diameter ; lti6 air valves with stop 
valves, 4 in. diameter. These all require inspection, 
cleaning, oiling, and other attention from time to time 
to maintain them in good working order. 
The main pipe is laid either in or alongside the public 
road from Colombo to Hanwella. Fur this distance 
the country is subject to floods two or three times a 
year, for several days together, and these floods rise 
to a maximum, as in 1872 and 1883, of 12 and 17 ft. 
ra peotively, above the road and pipe. 
The road is in many places embanked, and generally the 
permanent water-level of the country is only about 4 to 
5 It., even in the driest times, below the surface. It 
therefore was necessary to keep the main pipe above the 
permanent water-level and as high as possible in cross- 
ing streams in reference to the flood and to the free 
drainage and escape of water from the land. This neces- 
sity required numerous and wide openings over drai- 
nage outlets aad streams. There are thus 56 crossings 
in all ; of these, 42 vary from 6 to 24 ft. openings apd 
14 vary from 48 to 196 ft, in length. 
The foundations of these bridges are below the ordi- 
nary water-level, and 60 of the piers are founded below 
sea and permanent water-level. The ground oonsiats of 
beds, of sand, gravel, clay, and peat and soft deposit, 
alternating, and to avoid deep foundation, such as iron 
cylinders, the piers were made solid blocks of brickwork 
with as wide a base as possible, so that they could be 
