es and weathers, the
upward beam is attached by a ring just as would be done if the tank
itself constituted the bottom.

One main reason for this arrangement is that the resistance of the
beam to the water as it rocks backwards and forwards wastes to some
extent the power generated by the force of the waves; and the greater
the length of the beam, the longer must be the distance through which
it has to travel when the buoys draw it into positions vertical to
that of the framework. A thin steel pipe offers less resistance than a
wooden beam of equal strength, besides facilitating the use of a
simple device for enabling the frame and buoys to slide easily up and
down.

The generally fatal defect of those inventions which have been
designed in the past with the object of utilising wave-power has
arisen from the mistake of placing too much of the machinery in the
sea. The device of erecting in the water an adjustable reservoir to
catch the wave crests and to use the power derived from them as the
water escaped through a water-wheel was patented in 1869. Nearly
twenty years later another scheme was brought out depending upon the
working of a large pump fixed far under the surface, and connected
with the shore so that, when operated by the rising and falling of
floats upon the waves, it would drive a supply of water into an
elevated reservoir on shore, from which, on escaping down the cliff,
the pressure of the water would be utilised to work a turbine.

Earlier devices included the building of a mill upon a rocking barge,
having weights and pulleys adjusted to run the machinery on board; and
also a revolving float so constructed that each successive wave would
turn one portion, but the latter would then be held firm by a toothed
wheel and ratchet until another impulse would be given to it in the
same direction. This plan included certain elements of the simple
system already described; but it is obvious that some of its floating
parts might with advantage have been removed to the shore end, where
they would not only be available for ready inspection and adjustment,
but also be out of harm's way in rough weather.

Different wave-lengths, as already explained, correspond to various
periods in the pendulous swing of floating bodies. Examples have been
cited by Mr. Vaughan Cornish, M. Sc., in _Knowledge_, 2nd March, 1896,
as follows: "A wave-length of fifty feet corresponds to a period of
two and a half seconds, while one o