ate shaft consists in the application of a nut
to the end of each pin, where it passes through the eye, the projecting end
of the pin being formed with a thread upon which the nut is screwed.

629. _Q._--Will you describe the eccentric and eccentric rod?

[Illustration: Fig. 51. ECCENTRIC AND ROD. Messrs. Penn.]

_A._--The eccentric and eccentric rod are shown in fig. 51. The eccentric
is put on the crank shaft in two halves, joined in the diameter of largest
eccentricity by means of a single bolt passing through lugs on the central
eye, and the back balance is made in a separate piece five eighths of an
inch thick, and is attached by means of two bolts, which also help to bind
the halves of the eccentric together. The eccentric strap is half an inch
thick, and 1-1/4 inch broad, and the flanges of the eccentric, within which
the strap works, are each three eighths of an inch thick. The eccentric rod
is attached to the eccentric hoop by means of two bolts passing through
lugs upon the rod, and tapped into a square boss upon the hoop; and pieces
of iron, of a greater or less thickness, are interposed between the
surfaces in setting the valve, to make the eccentric rod of the right
length. The eccentric rod is kept in gear by the push of a small horizontal
rod, attached to a vertical blade spring, and it is thrown out of gear by
means of the ordinary disengaging apparatus, which acts in opposition to
the spring, as, in cases where the eccentric rod is not vertical, it acts
in opposition to the gravity of the rod.

630. _Q._--Will you explain in detail the construction of the valve
gearing, or such parts of it as are peculiar to the oscillating engine?

_A._--The eccentric rod is attached by a pin, 1 inch in diameter, to an
open curved link or sector with a tail projecting upward and passing
through an eye to guide the link in a vertical motion. The link is formed
of iron case-hardened, and is 2-3/4 inches deep at the middle, and 2-3/8
inches deep at the ends, and 1 inch broad. The opening in the link, which
extends nearly its entire length, is 1-5/16 inch broad; and into this
opening a brass block 2 inches long is truly fitted, there being a hole
through the block 3/4 inch diameter, for the reception of the pin of the
valve shaft lever. The valve shaft is 1-3/4 inch diameter at the end next
the link or segment, and diminishes regularly to the other end, but its
cross section assumes the form of an octagon in its passage