high above the
engine platform, and the elevation to the centre of the guides or the
centre of the shaft is 10 inches higher than this. The metal both of the
side frames and bottom flange is 1-1/4 inch thick. The cylinder has flanges
cast on its sides, upon which it rests on the bottom frame, and it is sunk
between the sides of the frame so as to bring the centre of the cylinder in
the same plane as the centre of the screw shaft. The opening left at the
guides for the reception of the guide blocks is 6 inches deep, and the
breadth of the bearing surface is 11 inches. The cover of the guides is 8
inches deep at the middle, and about half the depth at the ends, and holes
are cored through the central web for two oil cups on each guide. The brass
for each of the crank shaft bearings is cut into four pieces so that it may
be tightened in the up and down direction by the bolts, which secure the
plummer block cap, and tightened in the athwartship direction, which is the
direction of the strain, by screwing up a wedge-formed plate against the
side of the brass, a parallel plate being applied to the other side of the
brass, which may be withdrawn to get out the wedge piece when the shaft
requires to be lifted out of its place. The air pump is bolted to one side
of the bottom frame, and a passage is cast on it conducting from the
condenser to the air pump. In this passage the inlet and outlet valves at
each end of the air pump are situated, and appropriate doors are formed
above them to make them easily accessible. The outlet passage leading from
the air pump communicates with the waste water pipe, through which the
water expelled by the air pump is discharged overboard.

645. _Q._--Is the cylinder of the usual strength and configuration?

_A._--The cylinder is formed of cast iron in the usual way, and is 1-1/8
inch thick in the barrel. The ends are of the same thickness, but are each
stiffened with six strong feathers. The piston is cast open. The bottom of
it is 5/8ths of an inch thick, and it is stiffened by six feathers 3/4 of
an inch thick; but the feather connecting the piston rod eyes is 1-1/4 inch
thick, and the metal round the eyes is 2 inches thick. The piston is closed
by a disc or cover 5/8ths of an inch thick, secured by 15 bolts, and this
cover answers also the purpose of a junk ring. The piston packing consists
of a single cast iron ring 3-1/2 inches broad, and 1/2 inch thick, packed
behind with hemp. This ring is