e size, moored in position at a convenient distance
from a rock-bound ocean coast, will supply the first idea of a
wave-motor on this primary principle as adapted for the generation of
power. On the cliff a high derrick is erected. Over a pulley or wheel
on the top of this there is passed a wire-rope cable fastened on the
seaward side to the buoy, and on the landward side to the machinery in
the engine-house. The whole arrangement in fact is very similar in
appearance to the "poppet-head" and surface buildings that may be seen
at any well-equipped mine. The difference in principle, of course, is
that while on a mine the engine-house is supplying power to the other
side of the derrick, the relations are reversed in the wave-motor, the
energy being passed from the sea across into the engine-house. The
reciprocating, or backward and forward, movement imparted to the cable
by the rising and falling of the buoy now requires to be converted
into a force exerted in one direction. In the steam-engine and in
other machines of similar type, the problem is simplified by the
uniform length of the stroke made by the piston, so that devices such
as the crank and eccentric circular discs are readily applicable to
the securing of a rotatory motion for a fly-wheel from a reciprocating
motion in the cylinders. In the application of wave-power provision
must be made for the utilisation of the force derived from movements
of _differing lengths_, as well as of _differing characters_, in the
force of impact. Every movement of the buoy which imparts motion to
the pulley on top of the derrick must be converted into an additional
impetus to a fly-wheel always running in the same direction.

The spur-wheel and ratchet, as at present largely used in machinery,
offer a rough and ready means of solving this problem, but two very
important improvements must be effected before full advantage can be
taken of the principle involved. In the first place it is obvious that
if a ratchet runs freely in one direction and only catches on the
tooth of the spur-wheel when it is drawn in the other, the power
developed and used is concentrated on one stroke, when it might, with
greater advantage, be divided between the two; and in the second place
the shock occasioned by the striking of the ratchet against the tooth
when it just misses catching one of the teeth and is then forced along
the whole length of the tooth gathering energy as it goes, must add
greatly to