EXPLANATION OF THE PLATES. 
39 Ï 
PLATE LV. b. 
This plate shews a longitudinal elevation of Humphrys’s engine. 
A A, Cylinder and jacket. 
C, The crank. 
D D, The steam-tight casing or trunk, which works up and down with the 
piston. 
H, The connecting rod, which vibrates freely within the steam-tight casing or 
trunk, as the crank revolves. 
a a, Slide valve boxes or nozles. 
c, Starting handle. 
d, Air-pump rod. 
e, Hot well. 
f Discharge pipe. 
h, Eccentric rod. 
k, Hand pump for supplying the boilers with water when the engine is not working. 
/, Throttle valve. 
m, Steam pipe. 
n, Small pipe for supplying the cylinder jacket with steam. 
u, Bilge pump. 
o, Relief valve connected with the feeding apparatus, by which the water escapes 
into the hot well when it is shut off from the boiler. 
PLATE LVI. a. 
This plate represents a midship section of the steam packet Dartford, shewing a 
front elevation of a pair of Humphrys’s engines of fifty horses’ power each. 
C C, Cranks. 
D, The trunk. 
H H, Connecting rods. 
aaaa, Slide valve boxes or nozles. 
c c, Starting handles. 
d, Air-pump rod. 
e, Hot well. 
ff Discharge pipes. 
h h, Eccentric rods. 
k, Hand pump. 
11, Throttle valves. 
m m, Steam pipes. 
p p, Balance weights of slide valves. 
r, Condenser. 
s, Air-pump. 
t, Injection cock. 
xocx, Foundation plate.