PROPELLING MACHINERY

167

boiler in which the water circulates inside tubes surrounded by the
fire and hot gases. Merchant ships are usually fitted with Scotch
boilers, installations of water-tube boilers only being common in
warships.

B

W

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o

K

Q

N

M

A
B

c

D

Fig. 3la —Single Ended Scotch Boiler (in section) without Mountings,

Shell Plate.

Top Manhole 16"x 12?.
End Plate.

Combustion Chamber Girders and
Stays.

Q

E Combustion

Plate.

F Combustion Chamber Back Hate.
G Combustion Chamber.
H Combustion Chamber Stays,
/ Back Tube Plate.
K Combustion Chamber Bottom Plate.
L Bridge X End Plate

NOTE.—Tubes and Girders omitted on Wing Combustion Chamber for simplicity.

Chamber Wrapper R

W

M Back Bearer.
N Firebars.
O Centre Furnace.
P Bottom Manhole 15" xllff.
Stay.
Stay.
S Front Tube Plate.
T Plain Tubes
U Stay Tubes.
V Stay Tubes with Nuts.
Longitudinal Joint Double Butt
Strap.