^7 4 History (^Mechanical Inventions. 
level of the water-line. The space directly under the pad- 
dle-wheel at h h, is also closed by a boarding or otherwise, at 
such a distance as exactly to clear the circumference of the 
paddle-wheel, at the same time that the hindermost part of 
the paddle-wheel (or towards the stern of the vessel) is left 
as open and free from obstruction as possible, as will be clear- 
ly seen by the section Fig. 7. By this arrangement and manner 
of inclosing the paddle-wheels, the water cannot escape laterally 
from the action of the paddles, neither can it escape downwards, 
but is obliged to enter at the aperture and be fairly driven 
out behind the paddle-wheel, v/here it will meet with no mate- 
rial obstruction; by which means the greatest possible effect is pro- 
duced by the paddle-wheels, to propel the vessel forwards through 
the w'ater ; at the same time the paddle-wheels would always be 
protected from being inj ured by the violence of the waves, and 
would be less impeded by back-water. 
The second of Mr Gordon’s improvements is applicable to 
sailing vessels as well as to steam-packets, being for the purpose 
of keeping a vessel perpendicular in the w'ater (or upon an even 
keel, as it is termed by seamen). It consists in employing one 
or more vessels or tanks, to be suspended over the weather-side 
of the ship at a considerable distance from the side. These ves- 
sels or tanks should be suspended, in such a manner as tp be 
capable of being lowered down into the sea, filled with water, 
and then drawn up to operate by their weight in counteracting 
the effect of the wind upon the vessel, and keeping her always 
upon an even keel, or nearly so, which is of very great import- 
ance, particularly in vessels or packets to be propelled by steam, 
in order that the paddle-wheels may act equally in the wa- 
ter on both sides of the vessel. The vessels or tanks above men- 
tioned may be made of wrought iron-plate, or of tarred canvas 
distended by a hoop, or any other suitable material, and be fur- 
nished with a guy-rope at bottom, for the purpose of turning 
out the water to empty the vessels or tanks, when the use of the 
weight becomes no longer necessary : they may be suspended 
from the ends of booms or davits over the ship’s side, or from 
turning jibs similar to a crane, so as to be capable of being 
turned in close against the side of the ship, when not in use. 
