be closed by gates as hereafter described. Each sill was fastened by
five 11/2 in. bolts driven into pine plugs forced into holes drilled
from 18 inches to 24 inches into the rock. The temporary rock was then
removed as far as possible, to allow a free flow of the water.

In the channels of which there are three, having an aggregate width of
about 650 feet, cribs 46 feet wide up and down stream were sunk. In the
deepest water, where the rock was uneven, they covered the whole bottom
up to about five feet of the level of the silts, and on top of that
isolated cribs, 46 in. X 6 in. and of the necessary height were placed
seven feet apart, as shown at C Figs 2 and 3. At other places similar
narrow cribs were placed on the rock, as shown at D, Figs 2 and 3. The
tops of all were brought to about the same level as the before mentioned
sills. The rock bottom was cleaned by divers of all bowlders, gravel,
etc. The cribs were built in the usual manner, of 12 in. X 12 in. timber
generally hemlock, and carefully fitted to the rock on which they stand.
They were fastened to the rock by 11/2 in. bolts, five on each side of a
crib, driven into pine plugs as mentioned for the sills. The drilling
was done by long runners from their tops. The upstream side of the cribs
were sheeted with 4 in. tamarack plank.

On top of these sills and cribs there was then placed all across river a
platform from 36 to 46 feet wide made up of sawed pine timber 12 in.
X 12 in., each piece being securely bolted to its neighbor and to the
sills and cribs below. It was also at intervals bolted through to the
rock.

On top of the "platform" there was next built a flat dam of the
sectional form shown by Fig 1. It was built of 12 in. X 12 in. sawed
pine timbers securely bolted at the crossings and to the platform, and