sheeted all over with tamarack 10 in. thick and the crest covered with
1/2 in. boiler plate 3 ft. wide. The whole structure was carefully filled
with stone--field stone, or "hard head" generally being used for the
purpose.

At this stage of the works, namely, in the fall of 1881 the structure
presented somewhat the appearance of a bridge with short spans. The
whole river--fortunately low--flowed through the sluices of which there
were 113 and also through a bulkhead which had been left alongside
of the slide with a water width of 60 ft. These openings had a total
sectional area of 4,400 sq. ft., and barely allowed the river to pass,
although, of course, somewhat assisted by leakage.

[Illustration: Fig. 1. CROSS SECTION IN DEEP WATER.]

It now only remained, to complete the dam, to close the openings. This
was done in a manner that can be readily understood by reference to
the cuts. Gates had been constructed with timber 10 in. thick, bolted
together. They were hung on strong wooden hinges and, before being
closed, laid back on the face of dam as shown at B, Figs. 1, 2, and 3.
They were all closed in a short time on the afternoon of 9th November,
1881. To do this it was simply necessary to turn them over, when the
strong current through the sluices carried them into their places, as
shown at A, Figs. 2 and 3 and by the dotted lines on Fig. 1. The closing
was a delicate as well as dangerous operation, but was as successfully
done as could be expected. No accident happened further than the
displacement of two or three of the gates. The openings thus left
were afterward filled up with timber and brushwood. The large opening
alongside of the slide was filled up by a crib built above and floated
into place.