ture of arcs
_which curve in the same direction_, whether the engine be running
forward or backward; whereas in the common modes of suspension the block
slip in one direction is substantially the half sum of the curvatures of
two arcs curving in opposite directions.

Consequently it would appear that the average action of the new
arrangement would be at least equal to that of the old in respect to
reducing the block slip when running in the intermediate gears, while in
the full gears it entirely obviates that objectionable feature.

* * * * *

THE NEW RUSSIAN TORPEDO BOAT, THE POTI.

The Russian government has just had built at the shipyards of Mr.
Normand, the celebrated Havre engineer, a torpedo boat called the Poti,
which we herewith illustrate. This vessel perceptibly differs from all
others of her class, at least as regards her model. Her extremities,
which are strongly depressed in the upperworks, and the excessive
inclination of her sides, give the boat as a whole a certain resemblance
to the rams of our navy, such as the Taureau and Tigre.

[Illustration: THE NEW RUSSIAN TORPEDO BOAT, THE "POTI".]

A transverse section of the Poti approaches an ellipse in shape. Her
water lines are exceedingly fine, and, in point of elegance, in no wise
cede to those of the most renowned yachts. The vessel is entirely of
steel, and her dimensions are as follows: Length, 28 meters; extreme
breadth, 3.6 meters; depth, 2.5 meters; draught, 1.9 meters;
displacement, 66 tons. The engine, which is a compound one, is of 600
H.P. The minimum speed required is 18 knots, or 33-34 meters, per hour,
and it will probably reach 40 kilometers.

The vessel will be armed with 4 Whitehead torpedoes of 5.8 m., and 2
Hotchkiss guns of 40 cm. Her supply of coal will be sufficient for a
voyage of 1000 nautical miles at a speed of 11 knots.--_L'Illustration_.

* * * * *

A NEW STEAMER PROPELLED BY HYDRAULIC REACTION.

The oar, the helix, and the paddle-wheel constitute at present the means
of propulsion that are exclusively employed when one has recourse to a
motive power for effecting the propulsion of a boat. The sail
constitutes an entirely different mode, and should not figure in our
enumeration, considering the essentially variable character of the force
utilized.

In all these propellers, we have only an imitation, very often a rude
one, of the processes w