btuse or
hollowed base and a more or less wavy or crisped margin. The flowers are
arranged in more or less crowded whorls, the whole forming a denser or
looser panicle; they are generally perfect, with six sepals, six stamens
and a three-sided ovary bearing three styles with much-divided stigmas.
The fruit is a triangular nut enveloped in the three enlarged leathery
inner sepals, one or all of which bear a tubercle. In the common or
broad-leaved dock, _Rumex obtusifolius_, the flower-stem is erect,
branching, and 18 in. to 3 ft. high, with large radical leaves,
heart-shaped at the base, and more or less blunt; the other leaves are
more pointed, and have shorter stalks. The whorls are many-flowered,
close to the stem and mostly leafless. The root is many-headed, black
externally and yellow within. The flowers appear from June to August. In
autumn the whole plant may become of a bright red colour. It is a
troublesome weed, common by roadsides and in fields, pastures and waste
places throughout Europe. The great water dock, _R. hydrolapathum_,
believed to be the _herba britannica_ of Pliny (_Nat. Hist._ xxv. 6), is
a tall-growing species; its root is used as an antiscorbutic. Other
British species are _R. crispus_; _R. conglomeratus_, the root of which
has been employed in dyeing; _R. sanguineus_ (bloody dock, or
bloodwort); _R. palustris_; _R. pulcher_ (fiddle dock), with
fiddle-shaped leaves; _R. maritimus_; _R. aquaticus_; _R. pratensis_.
The naturalized species, _R. alpinus_, or "monk's rhubarb," was early
cultivated in Great Britain, and was accounted an excellent remedy for
ague, but, like many other such drugs, is now discarded.

DOCK, in marine and river engineering. Vessels require to lie afloat
alongside quays provided with suitable appliances in sheltered sites in
order to discharge and take in cargoes conveniently and expeditiously;
and a basin constructed for this purpose, surrounded by quay walls, is
known as a dock. The term is specially applied to basins adjoining tidal
rivers, or close to the sea-coast, in which the water is maintained at a
fairly uniform level by gates, which are closed when the tide begins to
fall, as exemplified by the Liverpool and Havre docks (figs. 1 and 2).
Sometimes, however, at ports situated on tidal rivers near their tidal
limit, as at Glasgow (fig. 3), Hamburg and Rouen, and at some ports near
the sea-coast, such as Southampton (fig. 4) and New York, the tidal
range is su