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APPENDIX III.
CHEAP TRAINS AND TEAMS.
The formation of deep-level tube railways has recently opened
up new prospects for communication between the suburban and
central parts of London. Underlying the superficial patches of
estuarine gravel, sand, and loam on which London stands, there
is a vast bed of dense clay—so remarkable as to have been long
known geologically as "The London Clay." This vast substratum
of clay thins out towards Woolwich on the east and towards
Reading on the west; but under western London it is hundreds
of feet thick. This clay is absolutely impermeable to water; it is
so stiff that it can safely be tunnelled through and lined with
cast iron or brickwork so as to form a permanent tubular
tunnel with all the necessary passages for lifts, staircases, and
adits. The Greathead machine bores through this clay as a
cheesetaster bores through a cheese, and the excavated clay is
shipped off over the railed portion of the line without ever
coming to surface in the London streets. Such tube railways
run in a straight line from point to point; they run altogether
below the sewers, water,and gas pipes; the house-basements and onestory
underground railways; and they ventilate themselves.
These tube railways are worked and lighted by electric energy,
and they form an almost ideal means of transport.
In fact, London stands in an unrivalled position for constructing
communications between its suburban and central parts.
The street traffic of London may now be relieved to any extent that
is necessary, and suburban townships may be developed without
involving that intensification of pressure which is caused by preliminary
clearances and re-constructions at the centres. With
proper facilities for communication by means of deep-level tube
railways, private enterprise may be expected to develop around
London all the accommodation that may be required.
I see no reason why iron-lined tubes, driven some 50 feet
below the surface of the streets, should not serve for improved
intercepting main sewers. Such deep-level tubes in the impervious
London Clay would take all the sewage out of London without
defiling the river at any point. At outside stations the sewage
would rise to its level in sewage wells, and might be pumped to a
higher level and distributed over the land, or disposed of in other
ways. Such tubes would run under the Thames as easily as
elsewhere.