156 BINNEY'S CASE.

and natural, she must stop; because the object of her voyage must
there end.

There is a material difference between legislative enactments
relative to the formation of an improved river navigation, and those
in relation to proper navigable canals; because of the material dif-
ference between the two subjects. The forms and modes of the
two kinds of navigation, are essentially different; and therefore,
inferences and principles, fairly deducible from, or applicable to
one, cannot, with any propriety, be made from, or to the other.

The river Thames, in England, is navigable above London, for
a considerable distance; and the vessels, which pass up it, are all
provided with a self-moving power; many of them have a horse
on board, to be sent out for towing when it can be done. Sails
are used, where an opportunity offers, and where not, they use oars,
or setting-polls. For some spaces they have the privilege of a
towing path on the bank, from which the horse is made to tow the
boat; and in other spaces the horse is driven into the river, to
wade along, and drag the boat after him. On the river Severn, in
England, a towing path, from which vessels are drawn along
up or down the river, is claimed by custom and has been con-
firmed by statute, (v) In some spaces of river navigation, the
vessel is lifted up, or let down into short canals, and thus passed
by innavigable rapids; in others, its safe passage is secured by
means of dams, sluices, or cuts. The whole course of river navi-
gation is irregular in its modes of movement; but the vessel pro-
ceeds throughout by having with it, from the very port, whence it
sets forth, a moving power suited to each mode of navigation,
either of which may be used according as it may be most bene-
ficial; and that too, through a wide, deep, and occasionally a
rapidly descending stream. The act incorporating The Potomac
Company, furnishes a complete example of river navigation. By
that act the rapid headlong river Potomac, above tide, was to be
made navigable; its falls were to be surmounted by locks and
canals; its ripples were to be opened by cuts; and its shallows
were to be cleared so that boats might pass up or down with
safety.

Proper canal navigation is uniform in its movements and limited
to one kind of propelling power; that is, by means of a towing
path; and it is rarely, or ever permitted to use any other. The

(r) Hale de Port. Maris, 86, 23 Hen. 8, c. 12.