ecocking introduces another cartridge, and so on, until the
whole are discharged; the whole twenty-four can be discharged in as
many seconds!

After leaving this interesting exhibition, where I could have lingered
a whole day, I was joined by a friend, an American--a gentleman of
great attainments in science--to whose remarks I am indebted for the
following scraps. The Merrimac, when low--as when I saw it--is a
trifling stream, having a bottom of laminated rock, worn in channels
by the stream. At spring and fall, there is ten or fifteen feet of
depth; and to remedy this inequality, an important work was undertaken
and executed: to this we bent our way. It is a canal in form, but
should more properly be called a reservoir. It is 1-1/4 miles long, 100
feet wide, and 15 feet deep; of solid granite, sides and bottom--equal
in durability to any work, ancient or modern. It is about half way cut
through the solid granite rock, which in that part furnishes a natural
wall. My friend had watched its progress, and gave me many interesting
details of the engineering processes employed: among others, the
tremendous application of steam and gunpowder. An engine bored holes
in the rock fifteen feet deep and twelve inches in diameter; and these
were so placed, and in such numbers, that at a single blast 170 tons
of granite were blown into the air--an operation hardly conceivable.
This canal leaves the town in a westerly direction--being, at its
outset, about a quarter of a mile from the Merrimac, but gradually
approximating for a quarter of a mile, until it touches and unites
with that river. Between the two, is one of the prettiest of public
walks, ten feet wide, having rows of trees on each side, and
terminating in a point; being the end of a splendid granite wall, at
its base thirty feet thick, and tapering to half the thickness,
dividing the natural from the artificial stream. Here we come to a
point of great interest: on the right is an artificial dam across the
river, with two sharp lines at an angle of sixty-seven degrees, the
point meeting the stream, thus stopping the waters, and insuring a
supply for the reservoir, while it forms a cascade of about twenty
feet.

My friend gave me a very graphic description of the opening of the
works. The whole was built in a cofferdam, quite dry, and the opening
was a holiday. Every spot within sight was covered with spectators,
for whom the engineer had contrived a surprise. The works use