sure and the velocity of the pistons had been the same, then
a pressure of 2900 Lbs. upon the vertical paddles would have been balanced
by an equal pressure on the pistons, which would have been in this case
about .75 Lbs. per square inch; but as the effective velocity of the centre
of pressure is 4.997 feet per second, while that of the pistons is only
3.66 feet per second, the pressure must be increased in the proportion of
4.997 to 3.66 to establish an equilibrium of pressure, or, in other words,
it must be 1.02 Lbs. per square inch. It follows from this investigation,
that, in radial wheels, the greater part of the engine power is distributed
among the oblique floats.

558. _Q._--How comes this to be the case?

_A._--To understand how it happens that more power is expended upon the
oblique than upon the vertical floats, it is necessary to remember that the
only resistance upon the vertical paddle is that due to the difference of
velocity of the wheel and the ship; but if the wheel be supposed to be
immersed to its axle, so that the entering float strikes the water
horizontally, it is clear that the resistance on such float is that due to
the whole velocity of rotation; and that the resistance to the entering
float will be the same whether the vessel is in motion or not. The
resistance opposed to the rotation of any float increases from the position
of the vertical float-where the resistance is that due to the difference of
velocity of the wheel and vessel--until it reaches the plane of the axis,
supposing the wheel to be immersed so far, where the resistance is that due
to the whole velocity of rotation; and although in any oblique float the
total resistance cannot be considered operative in a horizontal direction,
yet the total resistance increases so rapidly on each side of the vertical
float, that the portion of it which is operative in the horizontal
direction, is in all ordinary cases of immersion very considerable. In the
feathering wheel, where there is little of this oblique action, the
resistance will be in the proportion of the square of the horizontal
velocities of the several floats, which may be represented by the
horizontal distances between them; and in the feathering wheel, the
vertical float having the greatest horizontal velocity will have the
greatest propelling effect.

559. _Q._--Should the floats in feathering wheels enter and leave the water
vertically?

_A._--The floats should be so govern