126 BUCKET'S CASE.—2 BLAND

"And the said president and directors, or a majority of them, are
hereby empowered and directed, if it can be conveniently done, to
answer both the purposes of navigation and water-works afore-
said, to enter into reasonable agreements with the proprietors of
such situation concerning the just proportion of the expenses of
* making large canals or cuts, capable of carrying such
loo quantities of water as may be sufficient for the purposes of
navigation and also for such water-works as aforesaid." The first
condition upon which an application of water may be made to
mills, as well as to navigation, is the consent of the proprietors.
But, supposing that to be given, still there are other conditions of
the most grave importance, which must all be complied with, be-
fore any water can be taken from these canals for mills. The com-
pany are empowered and directed to do so, "if it can be conve-
niently done to answer both purposes." This allows to them an
extent of discretion which cannot be duly appreciated without
adverting to the consequences of making a navigable canal tribu-
tary to mills as their head race.

The application of water as the propelling power of mills, requires
that it should flow in currents, no matter how rapid, so it does not
inundate the position of the mill; but the perfection of a naviga-
ble canal is, that the water it contains should be entirely motion-
less. The one use requires quick motion, and the other stillness.
Hence the unlimited application of the same volume of water; or
rather the having of water conducted along a cavity to answer both
purposes is absolutely and directly incompatible, (m)

To illustrate this, we must again recur to the diagram. Let A
D be the navigable canal twenty-five feet wide, and two feet deep,
made tributary to mill-sites as a head race. Suppose the whole
line from 4 to D, afforrds sites for mills; and that, within that
space, there is room for the erection of forty mills; then suppose
that the dimensions of the canal constructed, be " capable of car-
rying such quantities of water as may be sufficient " for twenty
mills only. It follows, that one-half of the mill-sites cannot be
occupied; and the other half must totally annihilate the naviga-
tion. But if the draft from the canal for mills be of such a vol-

(m) "One great and fatal error has been interwoven into the scheme of
the other canals, excepting only that of the Potomac. They have been dug
as much with a view to the erection of mills, as to the purposes of naviga-
tion. To fit them for mill-races, their descent is rapid, and their current
strong. They are liable, of course, to the variation of the quantity of water
in the river; they bring down with their current, the alluvium of the river;
bars are formed in them, as well by this alluvium, as by the land wash; and
their banks, where they are not of rock, or walled, are liable to perpetual
wear by the current. The canal is, besides, itself an inconvenient rapid to
those who would ascend it."—Per Latrobe, Report of A. Gallatin, Secretary
of the Treasury, on Roads and Canals, 1808, page 86.