When Corbulo commanded in the parts about the mouths of the Rhine, he employed his men in making a cut, 23 M. P. long, between the Mosa and the Rhenus, “qua incerta Oceani vetarentur.” (Tac. Ann. 11.20.
) Some critics have proposed to change “vetarentur” into “vitarentur,” but probably the text is right. Dio Cassius (60.30), who speaks of this canal, says that it was about 170 stadia long. If we take the usual estimate of the Roman mile, which is 8 stadia, the distance of Dion is somewhat too small, if the text of Tacitus is right.
The reason for making the canal which the Greek historian gives, was, “that the rivers might not flood the country, by having their waters driven back by the high tides;” an explanation which seems to agree with “vetarentur” in Tacitus, and to be a probable explanation of Corbulo's design.
There seems little doubt about the position of this canal, though there has been great difference of opinion.
It is the channel which runs from Leiden,
The distance agrees very well, and the position agrees with the purpose for which the canal was made.
The old Rhine, or the Rhine proper, runs past Leiden,
and was a more considerable stream in the Roman period than it is now.