ter, with
three blades and a rise of 6.3 meters, make with natural draught 105
revolutions, and with forced draught 120. The pumping apparatus are
able to lift in one hour 400 tons of water. The front boiler room
contains a special cylindrical boiler for the working of the
electrical apparatus, for hydraulic pumps of the artillery service,
for anchor windlasses, ventilators, fire engines, etc. The whole
engines weigh 890 tons. The bunkers have a capacity for 660 tons of
coal, which allows for a run of 4,500 sea miles.

* * * * *

CLARK'S GYROSCOPIC TORPEDOES.

Figs. 1 and 2 represent, upon a scale of about 1/10, two types of
torpedoes, the greatest number possible of the parts of which are made
revolvable, so as to render the torpedoes as dirigible as the gyrating
motion permits of.

Fig. 1 represents an electric torpedo actuated by accumulators, A A,
keyed upon the shaft, and revolving along with the gearings. At the
beginning of the running, the accumulators are not all coupled, but
under the action of a clockwork movement which is set in motion at the
moment of starting, metallic brushes descend one after another upon
the collectors, B, and set in action new batteries for keeping
constant or, if need be, accelerating the speed at the end of the
travel.

[Illustration: Fig. 1.]

[Illustration: Fig. 2. CLARK'S GYROSCOPIC TORPEDOES.]

Fig. 2 represents an air torpedo proposed by the same inventor. The
air reservoir, C, revolves along with the gearings under the action
of the pneumatic machine, D. The central shaft is hollow, so as to
serve as a conduit. The admission of air into the slide valve of the
machine is regulated by a clockwork which actuates a slide in an
aperture whose form and dimensions are so calculated that the speed
remains as constant as possible toward the end of the travel.

The trajectory of the two torpedoes is regulated by a cylindrical
bellows, F, which gives entrance to the sea water. The springs shown
in the figure balance the hydraulic pressure. The tension of these
springs is regulated by the rod, H, according to the indications of
the scale of depths, I.

When the torpedo reaches too great a depth, the action of the springs
can no longer balance the increase of the hydraulic pressure, and the
accumulation of the charge in the rear causes the front to rise toward
the surface. When the torpedo reaches the surface, a contrary action
is produced