On the intended Exeter Steam- Boat. 289 
the immersion of the vessel, and require it to be built of strong 
-and ponderous materials ; and after all, if a rope was attached to 
the stem of the vessel, and a weight equal to one-eighth the full 
power of the engine was fixed to the other end and passed over 
a pulley, the vessel would be drawn faster through the water than 
it could be impelled by the engine moving wheels ;—it therefore 
is a great desideratum to obtain an action on the water at once 
convenient in its application, and producing an effect equivalent 
to the moving power, which under such circumstances might be 
materially reduced. 
- Aware of the danger, waste of power, and inefficiency of wheels 
to move vessels deeply immersed aé sea, I devised.many sub- 
stitutes for them; but what I give a preference to, is a subaquatic 
lever, simple as the common oar; but which, owing to the 
adoption of a novel principle in its construction, possesses far 
greater power on the water; and which, when moved either up 
and down or to and fro therein, will communicate an unceasing 
forward motion to a body. 
I conceive it superior to the-common oar: Ist, In power: 
2diy, in being applicable with effect to the largest vessels aé 
sea: 3dly, in not requiring to be feathered: 4thly, in’ not losing 
time in rising out of the water. I conceive it superior to wheels 
in simplicity, possessing a better and equally unceasing action on 
the water, and far more convenient and secure in application, 
while its power of leverage may be increased almost ad infini- 
tum. Wheels cannot be multiplied or enlarged with corre- 
sponding effect or convenience; but a simple reciprocating lever, 
such as above described, may; because, like the feather in a wing, 
it will prevent little surface in the line of motion. A body wholly 
immersed in water is equally pressed and supported throughout, 
and therefore is not so liable to be broken as a wheel posited in 
air and water is. [I confess I have not as yet had an opportunity 
of trying this new species of lever on a large scale, 1 therefore 
naturally feel diffident in offering it to public notice: but I will 
show a model of it at work to any scientific gentleman, and ex- 
plain its peculiar properties and application to any person se- 
riously inclined to adopt the use of it. Except in diminishing 
the weight of the steam-engines used in vessels, and dismissing 
the fly wheel, I know of no valuable improvement that has taken 
place in steam-boats since they came intouse. ‘The cause | ap- 
prehend is, the vast expense of experiments in this line, and the 
very limited knowledge we possess of the laws and properties of 
fluids. ‘The House of Commons (the safety-valves of the purse 
of the nation) has humanely attempted to legislate for steam- 
boats, but has offered no rewards for their improvement. Since 
then, | have heard that the owners of a steam-packet on the 
Vol, 50, No,234. Oct, 1817, T Thames 
