There is no possibility of
adjusting them readily to suit variations in the speed of the current or
in the quantity of water required, nor of moving them from place to place
should this be convenient.
[Illustration: PARACHUTE HYDRAULIC MOTOR.]
The motor of Mr. Jagn is on a totally different principle. Its essential
features consist, as shown, of an endless rope made of hemp or aloe fiber,
which takes a turn or two round a pair of drums mounted on a barge or
pontoon, and then passes down the channel to return over a pulley hung
from a floating punt, at such a depth that the whole of the rope is
immersed in the water. Along this rope are suspended at equal intervals a
number of parachutes made of sail cloth. The rope passes through the
center of each of these, and to it are attached a series of strings, the
other ends of which are connected to the outside edge of the parachute.
Thus they act like the spokes of an umbrella to prevent the parachute from
opening too far under the pressure of the current. The parachutes must be
placed so far apart that the current may act fairly on each, and the sum
of the pressures forms the force which draws the rope through the water.
The moment, however, that any parachute has passed round the return
pulley, the current acts upon it in the opposite direction.
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