Chapter XXII: Part 22

_Jetties at the Mouth of Tidal Rivers._--Where a river is narrow near
its mouth, and its discharge is generally feeble, the sea is liable on
an exposed coast, when the tidal range is small, to block up its
outlet during severe storms. The river is thus forced to seek another
exit at a weak spot of the beach, which along a low coast may be at
some distance off; and this new outlet in its turn may be blocked up,
so that the river from time to time shifts the position of its mouth.
This inconvenient cycle of changes may be stopped by fixing the outlet
of the river at a suitable site, by carrying a jetty on each side of
this outlet across the beach, thereby concentrating its discharge in a
definite channel and protecting the mouth from being blocked up by
littoral drift. This system was long ago applied to the shifting
outlet of the river Yare to the south of Yarmouth, and has also been
successfully employed for fixing the wandering mouth of the Adur near
Shoreham, and of the Adour flowing into the Bay of Biscay below
Bayonne. When a new channel was cut across the Hook of Holland to
provide a straighter and deeper outlet channel for the river Maas,
forming the approach channel to Rotterdam, low, broad, parallel
jetties, composed of fascine mattresses weighted with stone (fig. 5),
were carried across the foreshore into the sea on either side of the
new mouth of the river, to protect the jetty channel from littoral
drift, and cause the discharge of the river to maintain it out to deep
water (see RIVER ENGINEERING). The channel, also, beyond the outlet of
the river Nervion into the Bay of Biscay has been regulated by
jetties; and by extending the south-west jetty out for nearly half a
mile with a curve concave towards the channel the outlet has not only
been protected to some extent from the easterly drift, but the bar in
front has been lowered by the scour produced by the discharge of the
river following the concave bend of the south-west jetty. As the outer
portion of this jetty was exposed to westerly storms from the Bay of
Biscay before the outer harbour was constructed, it has been given the
form and strength of a breakwater situated in shallow water (fig. 6).
(L. F. V.-H.)

JEVER, a town of Germany, in the grand-duchy of Oldenburg, 13 m. by rail N.W. of Wilhelmshaven, and connected with the North Sea by a navigable canal. Pop. (1901), 5486. The chief industries are weaving, spinning, dyeing, brewing and milling; there is also a trade in horses and cattle. The fathers (_Die Getreuen_) of the town used to send an annual birthday present of 101 plovers' eggs to Bismarck, with a dedication in verse.

The castle of Jever was built by Prince Edo Wiemken (d. 1410), the ruler of Jeverland, a populous district which in 1575 came under the rule of the dukes of Oldenburg. In 1603 it passed to the house of Anhalt and was later the property of the empress Catherine II. of Russia, a member of this family. In 1814 it came again into the possession of Oldenburg.

See D. Hohnholz, _Aus Jevers Vorgangenheit_ (Jever, 1886); Hagena,
_Jeverland bis zum Jahr_ 1500 (Oldenburg, 1902); and F. W. Riemann,
_Geschichte des Jeverlandes_ (Jever, 1896).

JEVEROS (JEBEROS, JIBAROS, JIVAROS or GIVAROS), a tribe of South American Indians on the upper Marañon, Peru, where they wander in the forests. The tribe has many branches and there are frequent tribal wars, but they have always united against a common enemy. Juan de Velasco declares them to be faithful, noble and amiable. They are brave and warlike, and though upon the conquest of Peru they temporarily submitted, a general insurrection in 1599 won them back their liberty. Curious dried human heads, supposed to have been objects of worship, have been found among the Jeveros (see _Ethnol. Soc. Trans._ 1862, W. Bollaert).