118 History of Mechanical Inventions and Useful Processes. 
bend back at Y, as shewn in the figures, and have the same 
diameter as those at L, with valves, opening outwards at their 
extremities. At the point S, beyond the junction of L L, the 
tube G is provided with a plug, by which it may be opened or 
shut at pleasure. Immediately above the tube G G is placed a 
tube R, which communicates with the suction-pipe of the pump 
for supplying the cistern E F with water, and which divides 
into two branches h 7t, Fig. 5, 6, which descend into the water 
on each side of the keel, and point aft, as in the figures. Above 
these branches is a plug P, by which the communication with 
the water may be opened or shut ; and there is a third tube, 
gg-> proceeding from both sides of it above the plug P, and 
proceeding at both its ends into the inside of the vessel, so that 
one end of it, by means of the plug q , shall draw water, while 
the other end, by the plug s , shall draw air from the inside of 
the vessel. Grates are placed at the end of the tubes h h, to 
keep out weeds and rubbish. 
The tube R communicates with E F by means of a tube V, 
with a stopcock placed below the plug P, that in case the tubes 
h h be obstructed, the engine may be stopped for an instant, 
and the plug FI shut, so that water being admitted from E F, 
by opening the stopcock, it will force out the obstruction. 
To the after side of E F, a pump of any convenient descrip- 
tion is applied, having its suction-pipe fixed on the tube R, and 
discharging itself into the cistern at N. By the operation of the 
plugs q or s , this pump may be made to pump air or water that 
has lodged in the hold, or, by shutting them, and opening the 
plug P, to pump water from the water on which the vessel floats 
into the condenser at N, through a valve opening into the 
cistern. 
The machine acts in the following manner. When the plug 
II of the pipe G is shut, the condenser E F is pumped half full 
of water, and the ping P being then shut, and s opened, air is 
pumped into E F, until it is ascertained by a common safety- 
valve T, that it contains as much air as it will sustain. 
The plug 5 being again shut, and p opened, so as to pump wa- 
ter, and the plugs H and O, O of the descending tube opened, 
and that at S shut, the water will proceed with great velocity 
through the tube G, and issue at the tubes L L (as long as the 
