156 BINNEY'S CASE.

look into the nature of the subject itself to ascertain whether there
are any principles of canalling which may, at this day, be con-
sidered as the settled common law in regard to the termination of
canals of this description, that indicate the point at which this
canal must be terminated.

For this purpose it will be necessary to understand what it is
that constitutes a port; to notice what is called improved river
navigation, in contrast with proper canal navigation; and to shew
where and how, by a kind of common consent, all canals of this
description have been terminated. The circumstances which will
be mentioned in relation to these matters, are such as are of
universal notoriety; and as are always recurred to as furnishing an
illustration of the causes which have always brought marine as
well as canal navigation to a termination at particular places; so
that the nature of the subject treated of in this law, and the prin-
ciples by which it should be construed may be fully understood.
Recollecting as we proceed, that all doubtful points are decided by
an application of general principles to the particular case, (p)

According to one of the most venerable of our legal authorities,
a port is a place for arriving and unlading of ships and vessels.
It has a city or town, called the head of the port, for receipt of
mariners and merchants, and the securing and vending their goods,
and victualling their ships. So that to constitute a port, it must
be a place to which vessels may have easy access from sea, and
where they may He in safety; and there should be houses and
suitable accommodations for mariners and merchandize as well as
a harbour for ships. But it sometimes happens, that the town, or
the head of the port, as it is called, is at some distance from the
port itself. This however, is always attended with great incon-
venience; and, therefore, in many instances, where it was practi-
cable, the navigation has been extended at an enormous expense
to the town or head of the port, (q) Anciently, the natural navi-
gation of the river Ex, in England, was such, that large ships
went quite up to the city of Exeter; but a malicious earl of
Devon, by throwing dams across the river, entirely choked the
channel, so that ships were obliged to stop four miles below, which
place was, for a long time, considered as the port. But at great
expense the obstructions were removed, and now ships again find

(p) Silk v. Prime, 1 Bro. C. C. 138. n.—(q) Hale de Port-Maris, 46,