The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1859-08-22
NEW YORK HERALD, MONDAY, AUGUST %, 1859

this workable water, and on its completion the
pumps were set to work The other form Of dam
was the ordinary cribbing Of the country; and owing
to the rapidity Of the stream unusual care and tact
had to be observed in its construction. 1t was
commenced with some preliminary cribbing, II we
may use the word, 20 wide and 100 long, con
suucted In approximate position as to the SITE OF
the pier, and placed transversely to the stream
above the ste Of the bridge.
The comparison between these two classes OF
dams may thus be made: The floating dam may DC
used several times-indeed one has been used four
times-and admits of the masonry being completed
IN one season, and, what 10 more, early IN the sea
son, and 1t has been found to answer best in deep
water It's disadvantage is that it could not be
made sufficiently strong TO resist the shove OF the
ice in the winter; hence it had to be removed he
fore the severe weather came. Consequently, when
The period arrived to construct the tube, the side
the pier was naked, and there was no point frosn
whence the scafiolding to support the tube truis
could start. With the Golfer dam this foundation
existed, and hence 1t was necessary TO frame one
centre scafOlding only, whereas with the floating
dams three such constructions were necessary, VIZ
the side of each pier. Nor was this consideration
an unimportant one, for such foundation was OBJ
tanned by. sinking scows and driving piles around
them to keep them in position. Otherwise the
framing was carried up above the height Of the
pier, and on the Gaping pieces was run railway,
to admit the passage OF travelling machine which,
mounted with crab. admitted q contrary passage
into position as easily a. pound weight is thrown
into scale. On the platform OF the dam wers
constructed sheds to cover the steam engine, the
blacksmiths shop, the storeroom and carpenter 4
shop; and thus the scene was presented of these
isolated areas Of an acre and quarter dotted
along the river, busy with life and ANNA
ton, and showing the work in It's various
stages. The dam perfected, the staging CON
structed, the travelling machine in position,
stone delivered ready for the mason Is lay
the anxious moment commeneed-thatO of pumping
out the water and getting in the foundation Not
that the labor was great 10 removing the water but
that the application of the test, to show the dams
were water tight and if the water would not force
its way up from below, naturally created anxiety.
Nothing could be better than the pumps used.
They were worked centrifugally, and threw 300
square-the diameter Of the pipe-and it was, more.
over one Of those portable affairs that man could
take on his shoulder and move from one place to
the other. 1t was calculated that these pumps
lowered the area of the dam at the rate OF two
feet an hour. Therefore in eight or ten hours the
dam was empty.
Three millions of cubic feet of masonry in the
Victoria BRIDGE That is to say if turned into
Iineal measure, it would reach SO miles; or az
solid would form pyramid 2l5 feet high, having
base Of 2l5 feet square These figures will give
some idea of the solidity of the structure and the
warrant that exists for its endurance for all time
The stone itself is mostly quarried from Point
Claire, and forms the first in the series of lower
silurian, and is known by the geological term of
chazy, resting Immediately ON the calciferous sand
rock and the Potsdam sandstone. At Point Claire
very extensive quarries have been in operation
since 1858, and the engineer student will be well
repaid by visiting them, for stones taken ont in
as large masses as in any quarry in the world We
see the proof of this fact in the dimensions of the
piers-the courses being feet 10 inches and
feet to feet inches to above water level, and
thence verging into course Is inches under
the plates, being in length from feet to IL feet.
One course of asblar of fe ct 10 inches was exam
amined by the writer the perimeter of the pier at
this point measured 200 feet 1t consists Of 80 stones
the lghtest of these weighing tons, the heaviest
II; the average weight Of the whole was l03 tons.
Such work may indeed be termed Cyclopean.
TUBES.
Each tube covers two openings-that is to say, it
is fixed in position in the centre, and is free to ex
pand or contract on the adjoining two piers. They
are l6 inches by 19 inches at the ends, but they
gradually increase to the centre, at which point
they are 16 feet by Il feet inches. The length
will accordingly be-
Feet.