Let us now imagine several beams of wood
shod with pointed iron fixed at the ends of strong levers,
projecting beyond the bow of the boat, as in the annexed
representation.
If these levers are at liberty to move up and down, and if
one or more projecting pieces, called cams, are fixed on the axis
opposite to the end of each lever, the action of the stream upon
the wheels will keep up a perpetual succession of blows. The
sharp-pointed shoe striking upon the rock at the bottom, will
continually detach small pieces, which the stream will
immediately carry off. Thus, by the mere action of the river
itself, a constant and most effectual system of pounding the rock
at its bottom is established. A single workman may, by the aid of
a rudder, direct the boat to any required part of the stream; and
when it is necessary to move up the rapid, as the channel is cut,
he can easily cause the boat to advance by means of a capstan.
53. When the object of the machinery just described has been
accomplished, and the channel is sufficiently deep, a slight
alteration converts the apparatus to another purpose almost
equally advantageous.
Pages:
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86