THE KANSAS CITY BRIDGE. 59

through holes drilled for the purpose. The other dredge was constructed espe-
cially for use on this pier; the tumblers were of hexagonal form, made of oak and
bound with wrought-iron; the chain links were only 12 inches long between
centres formed with upset ends; the buckets, whose form was novel, were
placed on every sixth link and held by the same pins by which the links were
coupled, an arrangement relieving the links of any transverse strain, the merit
of which was proved by the fact that the chain of this dredge never broke ; the
hexagonal tumbler was also found to give a steadier motion than the square
ones.*

A single line of shafting mounted on hangers attached to the trusses, and
driven by the engine on the floor below, extended from tie east end of the
house till opposite the western dredge ; on this shaft were placed four pulleys,
each arranged with clutch and lever, by which it could be thrown out of gear
independently of the others, and the power was carried to the dredges by belts
driven by these pulleys. The new dredge was mounted at the west end of the
pier, and the dredge at the east end was also provided with buckets of the new
pattern. These two dredges were worked through bevel gearing, the power
being transmitted at any elevation by a pinion sliding on a vertical shaft; the
other two were driven more directly by the belts, which were. kept tight under
all elevations by a loaded tightener sliding in a vertical frame; the latter
arrangement proved the better one. Hach dredge was completely boxed in
between the second and third floors, to confine the splash, thus keeping the
machinery and works upon the second floor dry and in good working order.
The dredges discharged towards the north, the sand falling on inclined troughs
which led to the lower platform, from which it was carried off in wheelbarrows,
on runways built for the purpose, and deposited a hundred feet north of the
works.

The machinery for handling stone was on the lower platform. It consisted
of a railway and cars, the same which had been used at Pier No. 1, running
along the west end of the works, and two travellers running lengthwise with the
pier, between the wells and the sides of the caisson. A floating derrick was

_ * A patent for the improvements in these dredges was issued to the authors of this work, bearing date
January 18, 1870.