138 BINNEY'S CASE.

the right to such waters, which the owners of the land, over which
they have been suffered to flow, have acquired by a kind of pre-
scription. It must be recollected, however, that the phrases 'sur-
plus water,' and 'waste water,' are nowhere to be found in the act
incorporating The Potomac Company; and that, in using those
expressions, facts are referred to, which are not mentioned at all in
that law.

It appears, among the circumstances of this case, that the canal
which this plaintiff has claimed the right so seriously to encumber,
if not to destroy as a navigable passage, by drawing off its waters
to mills, has not been in any manner protected at its upper entrance
from the wild ungovernable river, with which it is connected; the
freshets of which rise from fifteen to thirty feet above its low summer
level. In consequence of which, the canal, like its fountain, the
river, has its seasons of bursting fulness and of comparatively low
small volume. Left so exposed to the violences of the river, it is
by no means extraordinary, that there should be in the canal a
multitude of leaks, cracks, and rents from which great sluices of
water are continually gushing out. These escapes from the canal
may well enough be called 'waste water;' and they afford very
satisfactory evidence of the improper exposure and imperfect struc-
ture of the canal; but it seems to be a mistake to summon them up
as proofs of there being a regular amount of 'surplus water' in it,
sufficient for mills. They are facts, which prove, that the canal
has been very rudely and injuriously intruded upon by the river,
for want of guard-locks at its upper entrance, and nothing more.
Indeed so far from affording any evidence, that the canal has a
capacity to carry water sufficient for mills, as well as navigation,
they are proofs, that, for want of a guard-lock at its inlet, it is
alike unsafe and dangerous to both, since the swollen torrent,
which obstructs navigation, might sweep a mill to destruction, by
the same kind of force which rends and prostrates the banks and
mounds of the canal itself.

But it seems to be a still greater mistake as to the nature and
causes of these issues and sluices, to cite their long continuance as
furnishing a presumption, that the owners of the land, over which
they flow, have a right to consider them as permanent streams on
which they may erect mills. Presumptions of fact are conclusions
drawn from particular circumstances. They are such inferences as
are found by experience to be usually consequent upon or coinci-
dent with certain known facts. A presumption of right always