on the upper brass,
and 2 inches upon the lower brass, making a total depth of 4 inches. The
diameter of the bolts passing through the lugs is 1 inch, and the bolts are
tapped into the lower brass, and accurately fitted into the upper one, so
as to act as steady pins, as in the previous instance. The lower eye of the
connecting rod is forked, so as to admit the eye of the air pump rod; and
the pin which connects the two together is prolonged into a cross head, as
shown in fig. 50. The ends of this cross head move in guides. The forked
end of the connecting rod is fixed upon the cross head by means of a
feather, so that the cross head partakes of the motion of the connecting
rod, and a cap, similar to that attached to the piston rod, is attached to
the air pump rod, for connecting it with the cross head. The diameter of
the air pump rod is 1-1/2 inch, the external diameter of the socket
encircling the rod is 2-1/8 inches, and the depth of the socket 4-1/2
inches from the centre of the cross head. The depth of the cutter for
attaching the socket to the rod is 1 inch, and its thickness 5/16 inch. The
breadth of the lugs is 1-3/8 inch, the depth 1-1/4 inch, making a total
depth of 2-1/2 inches; and the diameter of the bolts seven eighths of an
inch. The diameter of the cross head at the centre is 2 inches, the
thickness of each jaw around the bearing 1 inch, and the breadth of each
9/16 inch.

628. _Q._--What are the dimensions of the crank shaft and cranks?

_A._--The diameter of the intermediate shaft journal is 4-3/16 inches, and
of the paddle shaft journal 4-3/8 inches; the length of the journal in each
case is 5 inches. The diameter of the large eye of the crank is 7 inches,
and the diameter of the hole through it is 4-3/8 inches; the diameter of
the small eye of the crank is 5-1/4 inches, the diameter of the hole
through it being 3 inches. The depth of the large eye is 4-1/4 inches, and
of the small eye 3-3/4 inches; the breadth of the web is 4 inches at the
shaft end, and 3 inches at the pin end, and the thickness of the web is
2-5/8 inches. The width of the notch forming the crank in the intermediate
shaft for working the air pump is 3-1/2 inches, and the width of each of
the arms of this crank is 3-15/16 inches. Both the outer and inner corners
of the crank are chamfered away, until the square part of the crank meets
the round of the shaft. The method of securing the cranks pins into the
crank eyes of the intermedi