Mr. T. W. Barber, M.Inst.C.E., and Mr. Jas. Casey, M.I.N.A., have
suggested that the difficulties of which the shipping interests complain
might be met by the construction of a barrage across the river from
Gravesend to Tilbury, a comparatively simple engineering feat after the
great Nile dam (about 1¼ miles in length), especially as the bed of the
stream is here firm chalk. This would, it is claimed, give a navigable
depth of water, varying from 65ft. at Gravesend to 32ft. at London
Bridge, without dredging, or any interference with the river bottom or
banks. Some of the advantages which would, the advocates of the scheme
claim, be secured are as follows:—Ships drawing 30ft. could proceed to
London Bridge at any hour of the day or night, without waiting for tides;
ships of all tonnages and draughts could traverse the river, anchor
anywhere, lie alongside any wharf or quay, always remain at one level
for loading or unloading, and need not lie out in the river or obstruct
the free navigation; dock entrances could be left open, thus saving the
cost and time lost in working them—the London and India Docks Company
estimates the cost of working their entrances at £50,000 per annum;
while greatly increased safety of navigation would result, there being
no possibility of grounding, swinging with the tides, or collisions due
to tidal drift. In addition to these, London would be provided free
with a lake of fresh water forty-five miles long, and from a quarter
to a half-mile wide. In short, we should have a vast inland lake from
Gravesend to Richmond.]
[Illustration: THE GREAT THAMES BARRAGE