e valve itself, operates as a stop, by
coming into contact with the disc which constitutes the bottom of the pump;
the disc being recessed opposite to the stop to enable the valve to open
sufficiently. This disc is bolted to the barrel of the pump by means of an
internal flange, and before it can be removed the pump must be lifted out
of its place. The air pump barrel is of brass to which is bolted a cast
iron mouth piece, with a port for carrying the water to the hot well;
within the hot well the delivery valve, which consists of a common flap
valve, is situated. The mouth piece and the air pump barrel are made tight
to the condenser, and to one another, by means of metallic joints carefully
scraped to a true surface, so that a little white or red lead interposed
makes an air tight joint. The air pump bucket is of brass, and the valve of
the bucket is of the common pot lid or spindle kind. The injection water
enters through a single cock in front of the condenser--the jet striking
against the barrel of the air pump. The air pump rod is maintained in its
vertical position by means of guides, the lower ends of which are bolted to
the mouth of the pump, and the upper to the oval in the top frame, within
which the air pump crank works; and the motion is communicated from this
crank to the pump rod by means of a short connected rod. The lower frame is
not set immediately below the top frame, but 2-1/2 inches behind it, and
the air pump and condenser are 2-1/2 inches nearer one edge of the lower
frame than the other.

622. _Q._--What are the dimensions of the cylinder?

_A._--The thickness of the metal of the cylinder is 9/16ths of an inch; the
depth of the belt of the cylinder is 9-1/2 inches, and its greatest
projection from the cylinder is 2-1/2 inches. The distance from the lower
edge of the belt to the bottom of the cylinder is 11-1/2 inches, and from
the upper edge of the belt to the top flange of the cylinder is 9 inches.
The trunnions are 7-1/4 inches diameter in the bearings, and 3-1/2 inches
in width; and the flanges to which the glands are attached for screwing in
the trunnion packings are 1-1/2 inch thick, and have 7/8ths of an inch of
projection. The width of the packing space round the trunnions is 5/8ths of
an inch, and the diameter of the pipe passing through the trunnion
4-5/8ths, which leaves 11/16ths for the thickness of the metal of the
bearing. Above and below each trunnion a feather runs from the edge of