r from which the sea has receded, has been provided
with deep access from the sea by a ship canal, as exemplified by
Amsterdam and Bruges; whilst Manchester has become a seaport by similar
works (see MANCHESTER SHIP CANAL). In such cases, however, perfectly
sheltered open basins are formed inland at the head of the ship canal,
in the most convenient available site; and the size of vessels that can
use the port depends wholly on the dimensions and facility of access of
the ship canal.

[Illustration: FIG. 8.--Barry Docks.]

Design of Docks.

Docks require to be so designed that they may provide the maximum
length of quays in proportion to the water area consistent with easy
access for vessels to the quays; but often the space available does
not admit of the adoption of the best forms, and the design has to be
made as suitable as practicable under the existing conditions. On this
account, and owing to the small size of vessels in former times, the
docks of old ports present a great variety in size and arrangement,
being for the most part narrow and small, forming a sort of string of
docks communicating with one another, and provided with locks or
entrances at suitable points for their common use, as noticeable in
the older London and Liverpool docks. Though narrow timber jetties
were introduced in some of the wider London docks for increasing the
length of quays by placing vessels alongside them, no definite
arrangement of docks was adopted in carrying out the large Victoria
and Albert docks between 1850 and 1880; whilst the Victoria dock was
made wide with solid quays, provided with warehouses, projecting from
the northern quay wall, thereby affording a large accommodation for
vessels lying end on to the north quay, the Albert dock subsequently
constructed was given about half the width of the earlier dock, but
made much longer, so that vessels lie alongside the north and south
quays in a long line. This change of form, however, was probably
dictated by the advantage of stretching across the remainder of the
wide bend, in order to obtain a second entrance in a lower reach of
the river. The Tilbury docks, the latest and lowest docks on the
Thames, were constructed on the most approved modern system,
consisting of a series of branch docks separated by wide,
well-equipped solid quays, and opening straight into a main dock or
basin communicating with the entran