HISTORY OF THE INVENTION.
2
The law which governs the distance which the water recedes is common to the
paddle wheel, and to all bodies moving in water.
There are few occupations in the pursuit of a philosophical truth more in
teresting than that of tracing an important invention from its birth as a crude
idea, and marking its progress until it becomes practical and efficient. In such
investigations, however, it is necessary to guard against attaching too much value
to these early notions, for in the majority of cases the application constitutes the
entire merit ; their suggestion being so obvious that the references of early writers
were evident,—so that the rarity with which such propositions are encountered
is frequently rather attributable to their being too generally known and admitted
to require comment, than to their being considered new and meritorious. And
thus many a valuable idea has been found to slumber for ages in the text books of
science until the maturity of the art to which it belongs renders it practicable.
To this class of mechanical arrangements the screw propeller may be considered
to belong ; and accordingly we find that there is nothing new in the idea of using
it to move vessels through the water. The instances we are about to quote furnish
sufficient evidence of this fact, and there is no doubt that further search would
swell the list of cases.
A proposal to use the screw as a hydraulic machine (in a manner approaching
so near the action of a propeller that the step thereto is clear and obvious), some
time before the year 1727, appears in the work entitled “ Machines et Inventions
approuvées par l’Académie Royale des Sciences, depuis 1727 jusqu’au 1731,”
in which is exhibited and described a machine for drawing vessels up a river
against the current, invented by M. Duquet. The arrangement will be apparent
by inspection of the diagram. 2
2 This diagram is correctly copied from the original work, hut is obviously erroneous, as the screw
should be considerably more immersed.
