116 History of Mechanical Inventions and Useful Processes . 
the communications which our correspondents may from time to 
time transmit to us on these subjects. 
1. Method of Propelling Steam Boats , without Wheels. By 
J. B. Fraser, Esq. Edinburgh. 
The great increase of steam-navigation has rendered it an 
object of no small -importance to simplify and improve the ma- 
chinery of steam-boats, and the great advantages that would 
arise from adopting them on artificial canals, has made it parti- 
cularly desirable to discover some new method of propelling 
vessels without the use of wheels. M. Bernoulli was, we believe, 
the first who suggested the idea of impelling boats by a jet of 
water. He proposed to fix in the boat an upright tube, in the 
shape of the letter L, the vertical part having a sort of funnel- 
top convenient for filling the tube with water, which descending 
through the horizontal part, and issuing in the middle of the 
stern, but below the surface of the water, should propel the 
boat by the re-action of the effluent stream. An improvement 
upon this contrivance was suggested by Dr Franklin, who pro- 
posed to add another tube of the shape L, 66 the two standing 
back to back, the forward one being worked as a pump, and 
sucking in the water at the head of the boat, would draw it for- 
ward, while pushed in the same direction by the force of the 
stern. And after all, he adds, it should be calculated whether 
the labour of pumping would be less than that of rowing. A 
fire-engine might possibly in some cases be applied in this opera- 
tion with advantage .” Dr Franklin then proceeds to shew how 
the boat might be moved by the use of air in place of water, and 
he suggests the use of an air-vessel properly valved to permit the 
force to continue, while a fresh stroke is taken by the lever.* 
In 1818, Dr Jeffrey of Glasgow took out a patent for propelling 
steam-boats by drawing and then forcing out through the same 
tube alternately, by means of a piston, a current of water in a di- 
rection parallel with that in which the boat was required to move ; 
but there were particular objections to this contrivance, which we 
understand have prevented it from coming into use. A similar 
* See the Memoirs of the Life and Writings of Benjamin Franklin, Vol. vx. 
p. 451. Lond. 1819. 
