Daily globe. [volume] (St. Paul, Minn.) 1878-1884, 1882-10-23


driven with a Nasmyth steam hammer.
Ground was first broken at the bridge
site on the 18th of May, 1881, when the
| small excavation was made for the east
abutment. On the following day the excs-
walton of the pit for the foundation of
pier l was begun, though little
! was done here until July.
On the 18th of July, 1881, the exca-
walton for the foundation of pier one was
resumed in earnest Although close to the
river this excavation was carried down
through the hard stratifed clay without
the aid of a pump, the only water found
IN the pit being strongly alkaline spring
water, which evidently had no connection
with the Missouri river, and which was
easily kept out by occasional bailing. The
first concrete in this foundation was put
In on the 9th of September, 1881, and on
the 1st of October the concrete filing was
finished. The laying OF masonry was be-
gun on the 18th of October, and the
pier completed on Nov. %. 1881. The
calsso1s on which piec and are founded
are built of pine timber, sheathed with
two thicknesses of three inch oak plank.
They measure seventy four feet long by
twenty-six feet wide, by seventeen feet
II OA t<O OQtSA0Cs lES 1OWGf pOTtlOu Oh
the caisson forms a working chamber sew
en- feet high, with flat roof and. inclined
sides. The upper portion of the caisson is
crib-work Of timber, filed throughout
with Portland cement concrete. Each
caisson contained 133, 1000 feet, board meas
ure, of timber, and $4,000 pounds of
iron, besides nearly 500 cubic
yards of concrete. The caissons
hII1If L., 4
and towed into position. After the Gals
son had been placed, the concrete above
the working chamber was put in, the air
locks put in position, and air pumped into
the working chamber, which was thus
converted into a great diving-belI, until
the water was expelled. A force OF men
chamber who excavated the sand. which
was carried off in columns of water, and
the caisson was forced down gradually by
its own weight as the excavation pro-
ceeded. The masonry was laid on the roof
of the caisson and continued as the sink
ing progressed, the top of the ma
sonry Icing always kept above water.
The first span erected was that between
piers one and two. The first iron was
placed on Thursday, July 81, 1882, and the
weight on Saturday, August 10. Exactly
four weeks later, OF Saturday, September
8, the second span, that between piers two
and three, was swung, and four weeks after
that, on Saturday. October Z, ne last span
carried its own weight, req uiring only the
addition Of the floor and the riveting of
some of the details 10 make the
bridge complete. The floor is formed of oak
7 hers nine inpboc md
long, spaced only six inches apart i'll the
clear. On this are laid the steel rails of
the track, inside of which are placed angle
irons of wrought iron, bolted to every tie
in manner which is believed to make the
floor perfectly safe from accident due to
derailment. The east approach to the
bridge leaves the old main line
at Bismarck station, and is exactly two
miles long. It differs in no essential re-
spect from other portions OF the Northern
Pacific railroad through this section Of the
country, except that some heavy work
and sharp curvature is encountered
on the face of the bluffs adjoining |
the bridge. The west approach is 5000 |
feet long from the west end of the perma-
nent bridge to the old track on the low bot
tom land between the river and Mandan.
This approach has grade of per cent. |
(52.S feet per mile), descending westward:
The eastern $500 feet of the west approach
is built across the space reclaimed from |
the Missouri river by the action of the
dyke, which is now sand bar already COW
cred with fair growth of willows. This
part of the approach consists of timber
trestle, the maximum height of which is
about sixty feet. This trestle spans the
main steamboat channel of 1880. which is
now willow swamp.