acement, 7,550
tons; maximum speed, 22 knots an hour; and she will have the enormous
indicated horse-power of 20,000. As to speed, the contractor guarantees
an average speed, in the open sea, under conditions prescribed by the
Navy Department, of twenty-one knots an hour, maintained for four
consecutive hours, during which period the air-pressure in the fire-room
must be kept within a prescribed limit. For every quarter of a knot
developed above the required guaranteed speed the contractor is to
receive a premium of $50,000 over and above the contract price; and for
each quarter of a knot that the vessel may fail of reaching the
guaranteed speed there is to be deducted from the contract price the sum
of $25,000. There seems to be no doubt among the naval experts that she
will meet the conditions as to speed, and this is a great desideratum,
since her chief function is to be to sweep the seas of an enemy's
commerce. To do her work she must be able to overhaul, in an ocean race,
the swiftest transatlantic passenger steamships afloat.

The triple-screw system is a most decided novelty. One of these screws
will be placed amidships, or on the line of the keel, as in ordinary
single-screw vessels, and the two others will be placed about fifteen
feet farther forward and above, one on each side, as is usual in
twin-screw vessels. The twin screws will diverge as they leave the hull,
giving additional room for the uninterrupted motion upon solid water of
all three simultaneously. There is one set of triple expansion engines
for each screw independently, thus allowing numerous combinations of
movements. For ordinary cruising the central screw alone will be used,
giving a speed of about fourteen knots; with the two side-screws alone,
a speed of seventeen knots can be maintained, and with all three screws
at work, at full power, a high speed of from twenty to twenty-two knots
can be got out of the vessel. This arrangement will allow the machinery
to be worked at its most economical number of revolutions at all rates
of the vessel's speed, and each engine can be used independently of the
others in propelling the vessel. The full steam pressure will be 160
pounds. The shafting is made of forged steel, 16-1/2 inches in diameter.
In fact, steel has been used wherever possible, so as to secure the
lightest, in weight, of machinery. There are ten boilers, six of which
are double-ended--that is, with furnaces in each end--21-1/4 feet long