and FLEVUM OSTIUM. Drusus, the son of Livia, and the brother of Tiberius, when he held a command on the Rhine, employed his men in making a canal to join the Rhine
and the Yssel.
This canal, called the Fossa Drusiana or Fossae Drusinae, commences below the separation of the Rhine
and joins the Yssel
(Tac. Ann. 2.8
; Suet. Cl. 1
.) Germanicus, the son of Drusus, passed with his ships from the Rhine,
through this canal, into the lakes and the ocean, and as far as the mouth of the Amisia (Ems
The water of the Rhine
being thus partly diverted into the Yssel
made a new outlet for that river, which outlet Pliny (4.15
) calls Flevum.
He says “that Helium and Flevum are the names of the two mouths into which the Rhine is divided, on the north flowing into lakes, on the west into the river Mosa; it preserves by an outlet intermediate between the two a moderate channel for its own name.” The Helium Ostium is the outlet of the Maas,
which now receives the Vahalis (Waal
The outlet of the Flevum Ostium was into a lake, which Mela (3.2) thus describes: “The Rhine not far from the sea is distributed in various directions, but to the left the Rhenus is a river even then and until it enters the sea; on the right it is at first narrow and like unto itself, afterwards the banks recede from one another far and wide; and now, no longer a river but a large lake, it is called Flevo where it has filled the plains; and surrounding an island of the same name it becomes again more contracted, and flows out again in the form of a river.” Mela here mentions only two mouths, but Ptolemy (4.9
), besides the outlet which he calls the Mosa [MOSA
], enumerates a western outlet of the Rhine, a middle outlet, and an eastern outlet; the last ought to correspond to the Flevum.
The lake which Mela describes corresponds to the Zuider Zee.
p. 151) observes that Mela does not say that the Flevum enters the sea; and he translates the last words, “iterumque fluvius emittitur,” “and comes as a river out of the lake.” He admits, however, that Mela assumed that the Flevum entered the sea; and nobody can doubt that, when Mela says it flows out again in the form of a river, he means to say that it enters the sea in a form like the other branch, though its course had been made different by passing through a great lake. Geographers have attempted to determine Mela's island, which is a useless attempt, for the lake has undergone great changes since Mela's time; and, besides that, his description may not be exact.
It is certain that there were large lakes, or a large lake, near the outlets of the Rhine;
for, besides the passage of Tacitus already mentioned, he says that Germanicus, on a previous occasion (Ann.
1.60), after sending Caecina through the country of the Bructeri to the Amisia, and appointing Pedo, who had the charge of the Frisian country, to command the cavalry, embarked four legions and took them through the lakes. Infantry, cavalry, and fleet all met at the Amisia.
These lakes then were navigable in the Roman period; and it is an erroneous, though common statement, that the Zuider Zee
did not exist then.
The enlargement that the Zuider Zee
has received by the encroachment of the sea has probably been chiefly on the west side, where the coast is flat and the water is shallow. Along the east side there is deeper water. In 1219 the sea is said to have broken in and to have carried away the dikes; and another invasion, in 1282, which did great damage, is also recorded.
It seems probable that the outlet of the Zuider Zee
is the part that has been chiefly enlarged, the part that lies north of the channel between Stavoren
for it is said that old Stavoren
was swallowed up by the sea.
It is conjectured by Walckenaer that the Nabalia of Tacitus (Tac. Hist. 5.26
) is the Yssel,
and that the Fossa of Drusus, from Arnheim
to the Yssel
formed, with the course of the Yssel
into the lake or lakes, the north-eastern limit of Gaul.
He further conjectures that the name Flevum was given to the stream which flowed out of the lake into the North sea. Accordingly, he supposes that the Castellum Flevum (Tac. Ann. 4.72
) may have been at the outlet of the Flevum, which channel completed the north-eastern limit of Gallia.
He further supposes that the island of Vlieland,
one of the four which lie in front of the Zuider Zee,
and form a barrier against the ocean, may represent the Flevum Castellum. (Walckenaer, Géog. des Gaules,
vol. ii. p. 294.)
Thus the Vlie-Stroom,
between the islands. of Vlieland
may represent the old mouth of the Flevum, as it subsisted before the great flood of the 13th century enlarged the lake Flevo, detached the islands of Schelling
from the main, and buried in its waters the numerous villages of the district of Stavoren.
(Walckenaer, vol. ii. p. 201.)