THE KANSAS CITY BRIDGE. 49

struction. A fortnight later the caisson struck upon one of the bearing piles,
which was pulled up from the outside, the platform over it having first been
sustained by trussing across between the two adjoining piles. At this depth
the work was also occasionally impeded by sand slides, the first notice of which
was given by a sudden rise-of the water inside of the caisson, a considerable
quantity of sand from the exterior slipping through under the cutting edge
and forcing the water before it, which increased the amount of excavation re-
quired and engendered a corresponding delay.

On the 6th of January very cold weather had set in ; three days later the
ice had jammed at the bridge line, and the river closed for the season. The ice
soon became so strong that the stones used in the masonry at Pier No. 6 were
taken across on wagons. To guard against the injury which might result from
the breaking up of this ice, the cluster of anchor piles was made into an ice-
breaker by surmounting it with a small triangular crib of square timber, to
which was fastened the upper end of a single inclined stick, the lower end of
which rested on the bottom of the river 15 yards above, being held down by
another small crib filled with stone ; a row of spring piles was also driven, extend-
ing from this ice-breaker to the instrument stand. A narrow opening, about
two feet wide, was cut in the ice on the channel side of these protections, extend-
ing some distance above them, by which the main field of ice was separated from
that nearer the shore which was attached to the piles. It was hoped that the
fields of ice would be broken into small cakes by the inclined timber, and that
these cakes would jam against the spring piles, pack to the bottom of the
river, and thus form a gorge above the pier site which should protect the
caisson from the shocks of the remaining ice. The trusses above the platform
were taken down, and everything not absolutely needed was removed toa place
of safety. About the same time a fourth section was added to the caisson ; it
was in all respects. similar to the third section, the walls filled with rubble
masonry, and it made the total height of caisson about forty feet.

On the 12th of February, the upper end of the cutting edge came to a
bearing on a point in the rock. The day previous the weather had become
warm, and the ice began to rot; on the 17th, at about noon, it broke and

moved down the river. The water was very low, 100.5, the current less than
7