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36
HARBOUR ENGINEERING.
quays, if the dues necessitated by the extra expenditure are confined to goods
using them.
“ But Madras may be made au improved port for shipping if a better dass
of barge can be used than the 2 to 10 ton lighters now in use. At present no
private owners, nor the Port Trust, can be expected to invest money in such
plant as tugs and 100-ton barges, which are practically certain to be wrecked
when a cyclone occurs, as it must occur once in some eight or ten years’ time.
The existing small craft corne ashore and not much harm is done, but bigger
craft would be wrecked to a certainty. Therefore the Port Trust authorities
have recently excavated a 6j-acre basin for such vessels, as well as for the Port’s
own dredging-plant, the floating timber trade, etc., and they have it in con-
templation to provide a few self-propelling 100-ton lighters, which, pending their
replacement by private enterprise, will be worked between ship and shore by
the Port authorities. There are now in use two steel jetties, one 800 feet long,
for imports, and the other 350 feet long, for exports. Another export jetty,
fully equipped with modern hydraulic cranes, is about to be erected, as well
as some wharves at the harbour breakwaters, alongside of which coal-ships
can lie and discharge during, probably, 300 days in the year. The new north-
eastern entrance, under its sheltering arm, and the closing of the old entrance,
will enable work to be done with far greater comfort and convenience and
less relative motion between ship and lighter or ship and coal-wharf than is
now possible.”
Respecting the shoaling difficulty, Mr Spring adds :—
“ The sandy shore of the thousand or so miles of the eastern coast of
India is continually being acted upon by surface waves dashing upon it, for
part of the year with a north-western set, and for part of the year with a
south-western set. The resultant of these two sets has a north-westerly trend,
and the effect is that wherever an obstruction juts out from the shore, e.g.
such an obstruction as is offered by a harbour arm, there is necessarily an
accretion of sand to the south of it, and the contrary, in the form of erosion,
to the north of it. The accretion is greatly assisted in its formation by the
effect of the wind upon the sand thrown up on the shore by the surface
waves; for it will be understood that in a tropical climate the sand is very
quickly dried by the intense solar heat. The prevailing winds, blowing for
months together in one direction, bear the dried sand landwards, and pile it
up until its level is from 3 to 5 fect above the level of high water. Such an
accretion, to the extent of some hundreds of acres, has found itself on the
south side of Madras harbour, affording valuable land for various port
purposes. It is in this accretion that the 6|-acre boat basin, previously
alluded to, has been excavated.
“ The sandy accretion has now extended itself nearly out to the extremity
of the south harbour arm, and the sea current, running for several months
in the year northward past the entrance, can be seen laden heavily with sand
in suspension, which, naturally, is being dropped in the entrance. The
entrance has thus, in the last ten years, been steadily shallowing at the rate