46 THE KANSAS CITY BRIDGE.

difficulty, by bracing them together with planks; they were then cut off and a
platform was built on top of them. The platform was found to sway five or six
inches with the current, a motion which was reduced as much as possible by ad-
ditional bracing; but on placing a transit upon the platform it was still found to
vibrate more than an inch, and therefore to be wholly unfit for its intended purpose.
The pier was accordingly located by measuring with a steel wire from Pier No. 1.

The pile driver was then moved to the pier site, and the piles driven for
the false works proper.* The first of these piles washed out almost as soon as
driven. It was evident that piles could be held here only by immediately bra-
cing them together ; for this purpose a plank was bolted on the side of the pile
by a single round bolt of inch iron, at such a height as to be near the surface of
the sand when driven home ; the plank, being left free to turn on the bolt, was
kept upright by lashing it to the side of the pile; after driving, it was to be
swung over and spiked to the top of the next pile below. Several piles were
tried in this way, but they all broke at the bolt hole under the concussion of the
hammer. An arrangement was then adopted which had been successfully used
at the bridge over the Rhine, at Coblentz. An iron ring, to lugs on the side of
which a long iron rod was fastened by a pin joint, was dropped over the head
of the pile when driven, and the rod made fast to the top of the pile below by
means of a stirrup ;f when found inconvenient to slip the ring over the top, it
was made of two parts, which were bolted together around the pile ; in spite of
this precaution one-fourth of the piles driven were lost. The distance between
the inside rows of piles was made 10 feet greater than the proposed width of
caisson, thus leaving five feet for clearance on each side—an allowance which
proved insufficient, as the piles, disturbed by the current and bruised against the
rock in the driving, were sometimes forced considerably out of place, and thereby
interfered with the caisson in its descent. The difficulties which attended this
work at this favorable season showed that it would have been impossible if
attempted during the floods of the previous months. |

When the piles had been driven and secured in this manner they were cut
off and capped, and a floor was placed over the whole. Upon this floor the erec-
tion of the caisson was begun on the 20th of October ; it was made similar in

 

 

* For plan of these works see Plate III. t See side elevation on Plate NL