ce lock, in which vessels can turn
on entering or leaving the docks (fig. 7). The most recently
constructed Liverpool docks, also, at the northern end have been given
this form; and the older docks adjoining them to the south have been
transformed by reconstruction into a similar series of branch docks
opening into a dock alongside the river wall, leading to a half-tide
basin or river entrances (fig. 1). The Manchester and Salford docks
were laid out on a precisely similar system, which was also adopted
for the most recent docks at Dunkirk (fig. 6) and Prince's dock at
Glasgow (fig. 3), and at some of the principal Rhine ports; whilst the
Alexandra dock at Hull resembles it in principle. The basins in
tideless seas have naturally been long formed in accordance with this
system (fig. 5). The Barry docks furnish an example of the special
arrangements for a coal-shipping port, with numerous coal-tips served
by sidings (fig. 8).

Tidal and half-tide basins.

Tidal basins, as they are termed, are generally interposed in the
docks of London between the entrance locks and the docks, with the
object of facilitating the passage of vessels out of and into the
docks before and after high water, by lowering the water in the basin
as soon as the tide has risen sufficiently, and opening the lock gates
directly a level has been formed with the tide in the river. Then the
vessels which have collected in the basin, when level with the dock,
are readily passed successively into the river. The incoming vessels
are next brought into the basin, and the gates are closed; and the
water in the basin having been raised to the level in the dock, the
gates shutting off the basin from the dock when the water was lowered
are opened, and the vessels are admitted to the dock. In this manner,
by means of an inner pair of gates, the basin can be used as a large
lock without unduly altering the water-level in the dock, and saves
the delay of locking most of the vessels out and in, the lock being
only used for the smaller vessels leaving early or coming in late on
the tide. Similar tidal basins have also been provided at Cardiff,
Penarth, Barry (fig. 8), Sunderland, Antwerp and other docks.

The large half-tide docks introduced at the most modern Liverpool
docks (fig. 1) serve a similar purpose as tidal basins; but being much
larger, and approached by entrances instead of locks