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EXPLANATION OF THE PLATES. 
Plate LIV. shews a longitudinal section of the engines. 
A, Steam pipes. 
B, Throttle valves for regulating the supply of steam to the engines. 
C, Blow valves for clearing the engines of air, by the admission of steam previous 
to starting. 
D, Inlet sluices and pipes, 11 inches’ diameter in the clear, for admitting the supply 
of water to the cold water pumps. 
E, Relief valves for the purpose of affording a ready escape for any accidental ac 
cumulation of water within the cylinders, either below or above the pistons. 
F, Humphrys’s metallic slides, by which the great pistons are actuated. 
G, The cold water pumps for forcing the water into the condensing cisterns H; 
these pumps are 18 inches’ diameter having a stroke of 2 feet 8 inches, and supposing 
their chambers to be quite filled with water at each stroke, will supply at the rate of 
8 gallons of water per minute per horse power, which is forced round the lower ex 
tremities of the condensing pipes and, ascending amongst them with considerable ve 
locity, escapes through apertures in the cisterns at their upper extremities, by the 
pipes marked L. 
H, Condensing cisterns; each cistern containing 2374 half inch copper pipes, 8 feet 
long each between the top and bottom plates, in which their ends are fixed, thus 
giving a total length of 18992 feet of pipe to each condenser exposed to the cold 
water, which is equivalent to 
18992 x 2 
285-4 H P 
= 133 lineal feet of \ inch pipe per horse 
power. 
I, Air pumps, 35 inches’ diameter and 3 feet stroke, by which the water and air is 
pumped out of the condensers and conducted by the pipes K to the casing or jacket 
surrounding the chimney, where it is warmed and perfectly separated from the air 
and descends through a stand pipe into the boilers by its hydrostatic pressure, as 
usual in the ordinary mode of feeding low pressure boilers. 
K, The feed pipes, 4 inches’ diameter; each pipe is provided with a stop valve to 
prevent the water returning from the casing around the chimney into the air pumps. 
L, Outlet pipes, 11 inches’ diameter in the clear, through which the water from the 
condensing cisterns is conducted outside of the vessel. 
M, Bilge pumps. 
0, Starting handles for working the slide valves.