that the motion of the pin, A, relatively to the rocker arm is one of
vibration about the moving center, J; and its motion relatively to the
sliding block, E, is one of vibration about the center, P, whose motion
relatively to E is a small amount of sliding in the direction of the
slot, due to the fact that the rocker arm itself, which virtually
carries the block, E, vibrates about O, while the suspension-rod, S,
vibrates about another fixed center. It will thus be seen that, finally,
the block slip will be determined by the difference in curvature 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,