With the Compliments of WILLARD S. POPE,
President and Engineer DETROIT BRIDGE AND
IRON WORKS.








MEMO IR
OF THE
IRON BRIDGE
OVER THE MISSOURI RIVER,
AT ST. JOSEPH, MO.
BIUILT IN 18 71-  -3,
BY THE
Detroit Bridge & Iron Works,
OF DETROIT, MICH.








HTISTORY OF THE BRIDGE,
How and When the Work was Done.
The project of the construction of a permanent bridge over
the Missouri river at St. Joseph, had for many years been a
subject of earnest discussion arlonig the residents of that city.
During'the latter part of 1870, a number of private citizens subscribed stock, organized a company to be styled the
"St. Joseph Bridge Building Company," prepared their articles of association, -and were incorporated.
At the first meeting of the incorporators, who were:
W. P. HALL,          J. M. HAWLEY,       J. H. R. CUNDIFF,
J. 13. HINMAN,       JOHN L. BITTINGER,   JAMES A. MATNEY,
O. M. SMITH,         I. G. KAPPNER,      JOHN PINGER,
J. D. MCNEELY,       WM. Z. RANSOM,      MORDECAI OLIVER,
I. C. PARKER,
all of St. Joseph, Mo., they proceeded with the election of
officers, to hold their respective terms for one year, with the
following result:
President.-Willard P. HIall.
Vice-President.-W. Z. Ransorm.
Treasurer.-I. G. Kappner.
Auditor.-John Pinlger.
Secretary.-J. M. Hawley.
F'nance 6ornmmittee.-Willard P. Hall, I. G. Kappner and
James A. Matney.




4
Commnittee on, Survey.-Willard P. Hall, J. M. Hawley and
J. B. Itinman.
On the 25th daty of January. 1871, there was submitted
to the vote of the people of the city, an ordinance authorizing
a subscription of -five thousand slhares of the capital stock of
the " St. Joseph Bridge Building Company," ainounting to
five hundred thousand dollars, the bonds payable at the
National Bank of Commerce, in the city of New York, twenty
years after their date, bearing interest at the rate of ten per
cent. per annum. The vote resulted in a remarkable majority
-only nineteen votes against.
In the latter part of January, 1871, Col. E. D. Mason was
engaged as Chief Engineer, and under his direction a survey
of the river was made, beginning at Belmont, about six miles
above St. Joseph, and extending to Palermo, about an equal
distance below.
In locating the bridge, Col. Mason chose a site just below
the city, at a place which affords the most distinct and stable
low water channel, sufficient area at high water, the least
impediment to the navigation of the river, and the most convenient approaches for rail and wagon roads.
His estimate of the cost of the bridge proper, finished in
place, with wagon and railroad connections on each side, was
as follows:'uperstructure, -                            $280,000
Substructure,   -    -   -   -   -   -    435,000
Riprap for protecting banks in the immediate
vicinity of abutments,    -   -   -        20,000
East approach complete,  -   -   -   -         10,000
West approach complete,  -   -   -   -         20000
$765,000
The original ordinance of the city, subscribing $500,000




5
required an expenditure of $100,000 by the Company, before
$50,000 of the city bonds could be touched, and $100,000 more
in order that the second $50.000 could be secured, and so on.
Although every effort of the Directors of the Bridge Company
was made to raise by private subscription $200,000, the suin
necessary to commence work, only $18,000 of that sum had
been raised.
The Council met on the 2d of Mav to revise and modify
the ordinance creating the former subscription, so as to authorize the payment of' fifty per cent. of'the city's subscription
bonds, on calls.
Tuesday, May 23d, the election for the amended bridge
ordinance was held, and was carried by an overwhelming
majority-a manifest evidence that the people of St. Joseph
were fully aroused to the vast importance of spanning the
river between the Missouri and Kansas shores with a bridge
at that point, at the earliest possible moment.
The balance of the money required to complete the bridge
was subsequently borrowed, and a mortgage placed upon the
structure to secure the same.
The great enterprise was at last under way, and the day
had come for opening the sealed proposals, June 10, 1871.
Tenders were received from all the large and responsible
bridge building companies in the country; and after the reading of the proposals, the Directory proceeded to consider the
bids, when the following resolution was unanimously adopted:
Resolved, That, whereas, the Detroit Bridge and Iron WVorks has
shown its capacity for bridge-building, by building bridges at Burlington, Quincy and Hannibal, and now has boats and all necessary
machinery, &c., for the prosecution of the work; therefore this Company accepts the bid of the Detroit Bridge and Iron Works, it being
the best and lowest bid.
The amount of the bond to be given by the contractor for




the faithful performr:alce of its contract, was fixed at the sumn
of $100.000.
It was furthermore resolved that the President of the Coinpany be directed to enter into a contract'with thie Detroit
Bridge and Iron Works to build the bridge -tfor the sumI specified in its bid, to-wit: $718,000.
After the making of the contract, the work was irimediately begun.  A sib-contract was made by the Detroit Bridge
and Iron Works with Axtell & Scoville, to deliver the stone
for the substructure. The stone were quarried at White's
Camp, Kansas, on the'St. Joe and Denver City Railroad, 112
miles west of St. Joseph, and the first train load arrived on
the 25th of July, 1871.




CHARACTER OF THE STREAM
- AND -
CONTROL OF THE CHANNEL,
The difference between extreme high and low water lines,
was found to be 22 feet. It is rare however that such floods
occur as to make so great a difference. The highest water
recorded was in the summer of 1844. This line having been
ascertained at the site of the bridge, it was assumed as the
base of levels, and called 100. Low water line was consequently 78,-the elevation of the floor of the bridge being
112. The extreme limit of low water, viz: a8, was reached
only once during the progress of the work on the bridge; and
this was for a few hours only, and was occasioned by the
temporary subsidence of the water consequent upon thle formation of a heavy ice gorge above the bridge. Ordinary low
water is about 80, and ordinary high water about 95.
The ordinary speed of the current at low water, is about
22 miles per hour. A' high water, it runs at the rate generally of about 4A miles per hour, although occasionally owing
to temporary dams and obstructions from submerged bars, it
reaches a speed for short distances of 8 or 9 miles per hour.
The river bottom is bounded on each side by bluffs, which
are fromn four to eight,niles apart.  Between these bluffs the
stream wanders at will, in an exceedingly tortuous and serpentine course. Striking against the rocky bluff on one side,
it is deflected entirely across the bottom until it is arrested by
the opposite bluff; and thus it describes a continual series of




8
great loops.  The soil composing it iimmediate banks is very
light, fine, and friable, and seems to dissolve in the water
almost as readily as sugar. Wherever the current strikes the
bank, it yields at once.  The loose soil dropping into the
rapid stream is borne away in solution, until in eddies and
quiet reaches it is again deposited in sand bars. The water
in the river, especially at high stage, is tawny and almost
thick with its burden of sand. It is evident that such a current, striking against such banks, must continually change its
course and direction. So true is this, that the channel of the
Missouri river is a synonym for changeability and fickleness.
Its great loops are incessantly moving. A place which to-day
is hard, dry land and covered with trees, may soon be the
very mid-channel of' the river; and conversely, where che river
now flows broad, full and deep, may shortly be dry land.
The first point then to be settled was the certain and permanent control of the channel.  Otherwise changes might
occur which would leave the bridge high and dry inland.
Not only must the course of the river be fixed and maintained
permanently under the bridge, but still closer approximation
must be had. The navigable channel must be secured beyond
a peradventure, so as to pass directly and truly through the
passage-way under the draw span.  Unless the treacherous
river could be curbed and thorougllfyl  mastered, there would
be little hope for a permanent bridge.
This absorbing subject was carefully studied by the engineer, and a plan finally adopted and executed, the following
description of which is taken from a paper prepared by Col.
Mason, chief engineer, and read by himi Sept. 10, 1872, before
the Civil Engineers' Club of the Northwest, at Chicago.
This part of the work was not included in the contract of




9
the Detroit Bridge and Iron Works, but was performed by
days work under the irnllediate charge of the engiineer.
"When the head waters of the Missouri river pass the City
of St. Joseph, they have traveled 2,500 miles, and are increased
by all the streams flowing down the eastern slope of the Rocky
Mountains between the thirty-ninth and fiftieth parallels of north
latitude.
"The river:At that point is the drainaoge of 413,000 square miles
of water-shed, upon which there is an average rain-fall of 1974
inches.
"The elevation of low water in the Missouri river, at St.
Joseph, is stated by HUMPHREYS & ABBOTT to be 756 feet above
tide-water.  The mean elevation of its surface is, therefore, 760
feet above the tide-water.  It has about 480 miles further to go
before joining the Upper Mississippi, near Alton, where it is 381
feet above the level of the sea.  Fourteen hundred miles above
St. Joseph, Captain REYNOLDS found the surface to be 2,194 feet
above tide-water.
"Its average slope, therefore, for about nineteen hundred miles,
is ninety-six one-hundredths of a foot per mile; but the slope is
not uniform. Between eight hundred and a thousand miles above
St. Joseph, it is one and one-tenth feet; between four and six
hundred miles above, it is one foot; and from St. Joseph to the
Mississippi -river it is seventy-nine one hundredths of a foot per
mile.
" A careful survey for seven miles in the vicinity of St. Joseph, and observations for a year, show  an average slope of
eighty-two one-hundredths of a foot per mile.  The difference
between the slopes of the river at these different points is so
slight, compared with the great distances between - them, that
for any work of a local character the engineer may consider the
average slope, as lie finds it at any point above the confluence
of the Mississippi and below Fort Union, to be a constant quantity; and hereafter in speaking of the river, I would be understood as referring to it in the vicinity of St. Joseph.
" The distance between' the bluffs- of the Missouri in the vicinity
of St. Joseph is from  four to six miles.  They are generally
rocky, composed of nearly horizontal strata of limestone, sandstone, soapstone and drift, and covered with a marl concretion
sometimes called loess, supposed by some geologists to be identical
with the loess bluffs of the Rhine upon which grow the famous
vineyards.  There are sometimnes breaks in this rocky formation;
the city of St. Joseph is built in one about four miles wide; but
the bluff is continuous, and a gap between the rock formation
2




10
is generally filled with loess like that which caps the bluffs above
and below. During the present geological and meteorological condition of the country, the wanderings of the river cannot extend
beyond the bluffs.
"The valley between these two boundaries is'an alluvial plain,
through which the river cuts its way fiom bluff to bluff; making
eight complete crossings in a distance of thirty miles, measured
in  the direction of its general course.  These windings of the
river leave tongues of land alternately reaching from  one bluff
to within a few thousand feet of the other.  Inhabitants of the
towns built opposite the point of one of those tongues of land
have usually a constant fear lest some flood may cut through
the base of the peninsula, letting the channel run along the
opposite bluff; thereby leaving them  miles inland.  Such cases
have occurred within the, last few years; one at Forest City,
about twenty-five miies above, and one at Hamburg, near Nebraska City.  These fears have a depressing influence upon any
public work depending for success upon the permanency of the
bottom  lands.  The citizens of St. Joseph are not without their
fears; and although I do not say it is impossible that a cut-off'
should occur opposite the city, yet its improbability is so great
that for all practical purposes it may be considered impossible,
and should the danger of a cut-off appear at any timeLimminent, the engineer can avert it.
"Without maps, a particular description of the river and its
windings may be necessary to an understanding of the matter;
and here I may explain that all elevations given refer to a datum
line assumed at one hundred feet below the surface of tile flood of
1844, the highest known to civilized man.  This line is assumed
to be 776 feet above the sea."The city of St. Joseph is built upon the east side of the river
valley, partly on the loess bluff afid partly on the clay bottom lands,
the largest part of which is above the reach of the highest floods.
Beginning three miles above the town, the river leaves a rocky
bluff' on the east side and runs nearly west across the valley to
the rocky bluff' at Belmont; thence, with a sharp curve, it returns
to a loess bluff' in the upper part of the town of St. Joseph, called
Prospect Hill; thence, with an easy curve to the south, with a radius
of about 7,000 feet, it now flows along the clay bank in front of
the town for about three miles, when, having acquired a due
west course, it crosses the valley again and strikes the bluff'
above Palermo, about three and a half miles south of Belmont.
Thus the river has flowed about eighteen miles to accomplish
seven of its general course.
* Vide IHumphrey & Abbott.




11
"The channel, at low water, which we find to be 80, is from
three to five hundred feet wide, of very unequal depth, ranging
from five to twenty-five feet, with an average sectional area of
eighteen hundred  feet, and a mean velocity of two and fourtenths miles per hour.  The exceedingly irregular character of
the low water channel makes all measurements of this kind at
such a time very unsatisfactory.
"The following measurements were made under favorable circumstances, and I rely upon their correctness:
" At 86, the sectional area wds 13,126 square feet;  mean velocity, two and six-tenths miles per hour; discharge per second, 40,690
cubic feet.  At 92, the height of ordinary floods, the sectional
area is 25,450 square feet; mean velocity, three and seventy-fiveone-hundredth  miles per hour; discharge per second, 139,975
cubic feet.  At 92, the river is from  fifteen hundred to thirtyfive hundred  feet wide between  its proper banks.  When  it
subsides, it leaves these banks distinct; but the space between
them  is nearly filled' with sand-bars.
"The river, at low water, does not materially encroach upon
the high water banks; but, first cutting  its way through the
lower bars, around accumulations of driftwood and the higher
bars, it makes a channel which crosses the high-water channel
from  bank  to bank every two or three miles.  It then begins
cutting away the higher bars, depositing lower ones along its
own channe], and conducting itself, on a smaller scale, as did
the larger river before it.  Sometimes it cuts its way through the
base of a high bar, and makes a new  channel against the bank
opposite to that along which it ran a few hours before, leaving
the point of the bar an island.
"' The bottom lands appear to me to have been built up in three
different periods of time, each period depositing different materials,
and under different circumstances from  either of the others.
"' Let us suppose the present time to belong to the third period.
In the second period, the river at average flood was from two
to'three miles wide, and had an average elevation of 100. Its
highest floods must have reached  120; its low  water channel
was similar to the medium high-water of to-day.
" In the first period, great floods filled the valley, and the
river scoured its rocky bed with  boulders weighing tons.  Its
low-water channel was greater than the greatest floods of to-day.
Its deposits were boulders, gravel, coarse sand and clay. The
high clay bottoms which exist to-day have this deposit for their
source.
" The deposits of the second period were of fine sand and clay,
and are of great fertility. They are covered, when not cultivated,




with a heavy growth of timber, principally sycamore, oak and
elm, and some of the trees are of great size.  The deposits were
made in the low-water channel of the first period.  Their elevation is from 100 to 110.
" The deposits of the third period are silt and fine sand, having in them  but a trace of clay and organic matter.  The silt
and sand weigh from  61 to 86 pounds per cubic foot when dry
and loose, and from 74 to 97 dry and packed.  If not disturbed,
in a few years they become covered with a thick growth of
weeds, cottonwood and willows., They are known as " cottonwood bottoms."   A fact explaining the growth in height of the
newer bottoms in some places is, that sand and silt brought up
from  the newer bars during the winter and spring months by
the winds are deposited among the weeds and brush.  A new
bottom  within two miles of St. Joseph has grown five feet in
many places within the last year from this ca-use. The elevation
of these bottoms is from  94 to 100.
"Now, the low water of to-lay has very little effect upon the
deposits of the second period, and  the  high water of to-day,
equal to the low water of the second period, has small effect
upon the deposits of the first.  The low water of to-day is continually cutting away and changing the form  of the high-water
deposits, and the high water of to-day is annually disintegrating
and destroying the deposits of the second period. The low water
of the first period s metimes cuts through the base of bars
making islands.  In the second period, whichever side of the
island the river ran, the opposite channel was filled with its
deposits; and it is through these deposits that a cut-off is possible for the floods of to-day.  The wanderings of the river of
to-day are bounded, therefore, so far as cut-offs are concerned,
by the deposits of the first period.
In the tongue of land opposite St. Joseph, at the east end of
which the west abutment of the bridge now building across the Missouri river is placed, is a spine of this material extending from
the rock bluffs at Wrathena, between Belmont and Palermo, to
within a mile and a-half of the city. Evidences of struggles and
failures of the river in the second period to  cut off this point
are apparent in the direction of a steep bluff of the first deposits,
five to eight feet high, dividing this from the second formation.
The land composing the tongue  north of this spine is almost
wholly of the second formation; while around the east end and
along the south side both the second and third are generally
found.
" Although the general direction of the river bends may be
considered fixed, yet among the lighter clay and sand of the
second, and the light sand. of the third deposits, occupying the




13
low-water channel of the old river, seldom  less than  two, and
often three or four miles wide, the river wanders at will, and
no spot therein can be considered a safe foundation for an enduring structure without artificial protection from its encroachments.
To give such protection to the west approach to the bridge, and
to insure the passage of the channel of the river through the
draw at all times, were the ends sought to be gained by building dikes and shore protection last winter.
" The bridge now building over the Missouri river at St. Joseph
is located about a mile and a-quarter below Prospect Hill, nearly
in the center of the long bend in  front of the city, and the
embankment forming its west approach will rest for three-fourths
of a mile upon a part of the third deposit.  At that distance from
the river the approach reaches the first formation.  Every part
of this space has been occupied by the river within the past
fifty years. At the time the location of the bridge was made,
the channel of the river turned directly south from a point 1,200
feet west from  Prospect Hill, and ran Ithence south to within
half a mile of the bridge, at which point it impinged upon the
Kansas shore; thence easterly, parallel with the bridge about 3,500
feet to the clay bank  forming  the east shore, leaving a bar a
mile long and 2,000 feet wide, at an average elevation of 90, in
front of the city; thence, turning directly south, it formed the
lower part of the long bend above referred to.. "The preliminary surveys for this work were made in February,
1871.  The succeeding flood in June and July was small, enduring above 90 but eighteen days, and touching 93 only  a few
hours; but the action of the river on its west bank showed that
in five years it would cut through ithe deposits of the last fifty
years and reach its old westerly shore, lengthening the bar in
front of the city two miles, and leaving the bridge half a mile
from its eastern beach.
"The problem  was to stop the river where it was then running, and drive it three thousand feet east and through the bar
and against the clay bank, which was its eastern shore ten years
ago.  Work was begun for this purpose in October last, and by
the first of August, following, all of our objects were accomplished.'The manner in which this work was done, and the means
used, were as follows:
"From  a point on the west shore, three thousand feet southwesterly from Prospect Hill, a dike was projected into the river at
right angles with the current as it then ran, and continued in a
right line eighteen hundred feet. This dike inclines down stream
somewhat from a line at right angles with the general direction
of a high-water channel as corrected, the upper angle being about
70. deg.  It is called "Beard's dike."




14
"Again, from  a point on the west shore, 800 feet above the
bridge, and 3,200 feet along the shore below Beard's dike, another dike was built, starting at an angle of 45 deg... with the shore,
and inclining down stream, until at a distance of a hundred feet
from the bridge it has anr angle of 45. deg. with the general direction of the river, and is 1,100 feet fromn the east shore. This
dike is 1,200 feet long, and  is called " Weaver's dike."   The
point where it leaves the shore is immediately above the point
where the channel impinged upon the bank when returning, after
having been turned aside by Beard's dike, half built; and except
in one particular, which I shall hereafter mention,   I am satisfied
with the location of both dikes.
"The woodwork of Beard's dike is from  sixty to seventy feet
wide at the base, thirty feet wide at the top, and from  twelve
to thirty-six feet deep.  The lower side is vertical.  This woodwork is surmounted with a wall of rip-rap averaging twelve feet
wide and three feet high, placed three feet friom  the lower edge
of the woodwork,  The whole was built to the average height
of the bar on the opposite side of the river.
"It was known by extensive soundings that, along the site of
the (like, the bed rock had an elevation  of from  35 to 40, and
that on the top of the rock was a layer of boulders from five to
seven feet thick, covered with a stratum  of stiff clay from  four
to five feet thick; thence to bottom  of channel were the light
sands of the river bed.  The top of the clay is about 35 feet below the surface at low water.  I am  sure, from observations made
while sinking the caissons for the piers of the bridge, that the
river never scours through this layer of clay, although water
soundings show that it often reaches it.
" Weaver's dike was built of like materials to Beard's dike,
and over a similar foundation; but only to 82, except the one
hundred and fifty feet nearest shore, which is built to 96.  It
was designed that this dike should stop the action of the lowwater channel and resist the efforts of the next flood to cut a
deep channel on the west side of the river, after it should have
been deflected to the west by the bar, as it surely would be
after passing the east end of Beard's dike; yet the dike was left
low so that too great an obstruction would not be offered at once,
should an unusually high flood occur.
" Beard's dike was put and kept in position in the water while
building by first driving cottonwood piles about ten feet apart,
within a space thirty feet wide along the lower half of the line
of the proposed dike.  The piles were driven from  ten to fifteen
feet in the sand, left about three feet above water, and then
sharpened at the upper end so that they should not afford a




15
foundation for the brush and timber to be put between and upon
them.  Then young cottonwood and sycamore trees, from sixty to
seventy feet long, untrimmed, were laid in, parallel with the current, tops up stream, until the mass touched bottom, when finer
brush was laid on, and sand carted on from  the shore sufficient to
make a double road for teams. This road of sand effectually packed
and weighted the whole mass, and was kept high enough to allow
the passage of horses and carts above the piles.
" The first channel crossed was five hundred feet wide, and
when the work was begun, sixteen feet deep, with a velocity in
the centre of four miles per hour, and no sloughs debouched from
it on the east side for a distance  of two thousand feet above.
When about half way across, the dike obstructed the channel sufficiently to cause a difterence of level in the water above and below it of three-tenths of a foot, and the increased velocity of the
current consequent thereon enabled it to scour the bottom to a
depth 9f 26 feet. The river also commenced cutting into the bar
opposite, with a fair prospect of doing so as fast as we could build
in so deep and rapid a current.  It showed me, however, that the
dike once down offered a greater resistance to the current than did
the sand-bars, and I permitted myself to have no doubts of final
success on account of its failure thereafter.  The channel we were
attempting to cross was the principal one of three, separated by
islands of sand bars; the middle one was about seven hundred feet
wide, but too shallow  to be navigated by the ferry-boat at low
water, and the last one was a mnere slough, about three hundred
feet wide, and was fast filling up.
" About two thousand feet above the dike, the west channel
separated from the others.  At that point it was about eight hundred feet wide, and six or seven feet at its deepest.  A dike of' a
temporary character was built across its head, which turned nearly
all its waters into the other channels, and greatly lessened the
current at the main work, so much so that the washing away of
the bar ahead of us ceased.  r This temporary work was built of
willow brush, laid between small piles driven with a wooden mlaul
and weighted with a road of sand.  It was about fourteen feet
wide and eight hundred feet long, with its top about a foot above
water.  Before it was completed the channel scoured the bottom
in some places to a depth of from ten to eleven feet. In ten days'
time it changed the  lavigable channel to the middle one and
remained intact until the breaking up of the ice in February fol'
lowing, when about half of it was torn loose and floated away.
A bar with its surface at 89 now covers the remainder.  Until
after a rise of two feet in November, which nearly filled the channel behind it with sand, it withstood the pressure of a head of
water four-tenths of a foot high.




" After this dike had succeeded in turning the channel, Beard's
dike was completed in the manner in which it was begun, and
across the channel to an island about four hundred feet wide, with
a surface of 82.  Over the island, which was but a sandbar, the
dike was built without piles.  Upon reaching the river again, the
dike behind us was built to 88, the riprap wall put on, and a sand
road made upon it, by which to bring forward material.  The
river was now frozen over, and the current quite sluggish.  The
middle channel was crossed with the dike without having to work
in a greater depth than fourteen feet.  A narrow bar between the
middle and east channels, two feet under water, was'reached, and
the east end of the dike was finished by building a mole about one
hundred feet in diameter at the b3ttom. This was built by driving
eighty piles within the limit of its base, and piling up between
and upon them brush with the tops outward, in layers alternating
with riprap, to the height of the dike.  The layers of brush were
about four feet thick, and of riprap two. Upon the top of this
work, a mound of riprap was built to 93. Although the river has
scoured to a depth of 35 feet on the upper and east sides of the
mole, its total settlement since completion is less than six inches.
" By the time this work was completed, a deep channel, 490
feet wide, had cut through  the east channel or slougll before
mentioned, and had for its east shore the wide bar in front of
the town. It was deflected by the bar to the west, and, reaching across the old channel, struck Wreaver's dike nearly at right
angles at a point but a few feet from the shore end.  WVeaver's
dike, built in the same manner as Beard's dike, of piles,
brush, sand and riprap, had for its principal object the affording of resistance to this expected attack of the river upon the
West shore. The dikes were built in the form  and manner described, upon the hypothesis that should an impinging  current
scour the bottom and undermine the front of the dike, the front
part would settle and sink down until the lowest limit of scour
was reached, the back part remnainliig   without nmaterial change
of elevation.  The front of WVeaver's dike was built ia from tenl
to fifteen feet of water.  When the channel from  the end of
Beard's dike struck it, as before mentioned, it began scouring
and letting dowh the front as expected.  The point of the inmpingemelt of the current gradually passed down stream along the
face of the dike, and before the ice broke up the whole front of
the dike had reached  a depth averaging eighteen feet below
low-water.
"These dikes were finished about the middle of February. The
river was then frozen over with ice from  twelve to sixteen inches
thick, with a surface at 82k. The ice showed signs of breaking tiup
about the 20th of February, and on the 23d it started, the river sud



17
denly rising to 87. This soon cut a channel 650 feet wide opposite
the east end of Beard's dike. The channel appeared a river of rolling ice, scarcely any water being visible   Large masses were
forced against and entirely over Beard's dike, without injuring
the wall of stone or'moving any part of it.   Weaver's dike
being low, much ice escaped over it in from four to five feet
of water.
-" On the 24th a gorge of ice formed about four hundred feet
below the east end of Beard's dike, extending from  the east
shore of the river to Weaver's dike.  The gorge dammed the
river until it stood three feet higher above it than at the bridge,
distant about half a mile below.  The gorge broke first at
Weaver's dike, and in a few minutes the channel was scoured
to such a depth that it remained from  thirty to thirty-four feet
deep along the face of the dike after the ice was gone and
soundings could be made, with the river at 84.  The dike settled down in front with the scour-turned over, so to speakbut the wall of riprap remained at nearly the same height and
in the line where it was built.  Beard's dike across the middle
channel, settled about two feet.  This is probably as severe a
test of the ability of this form of dike to resist and turn aside
the river, as could be afforded under any circumstances.
"About the first of June, this year, (1872) the spring-flood had
reached 90, almost entirely submerging the great bar, and flowing over Beard's dike in a thin sheet, with a fall of from  six
to eleven inches.  And now began in earnest the work of removing the bar and making a new channel along the clay bank of
the east shore.  To do this required the taking away of at least
five million cubic yards of sand.  This was accomplished by the
middle of July, the flood averaging 93 meantime.
"The effect of the obstruction  to the current by Beard's
dike at this height of the river, was to make a lake of conparatively still water above it, extending to the current of the
flood then running along the bar opposite Prospect Hill. Through
this lake ran threads of current to supply the overflow of the
dike, strong enough to move sand along, but not to scour. The
dike standing firm, this lake was a constant force pressing the
current against the bar.  This the current attacked first at Prospect Hill, by eating into it abruptly fifty to a hundred feet,
forming what is called by river men a "pocket."  The pocket
once formed, it moved down stream, the current cutting away
the bar as the mower cuts a swath, and in a few  days would
pass below the dike and disappear. But before the first one had
done its work, the second and sometimes the third had begun,
and were following swiftly after. Meanwhile sand was deposited
3




18
along the line between the still water and the current, and as
the bar disappeared the current still pressed against it, crowded
by the still water, the line of the deposit passed eastward, the
new formed bar widened and became the west boundary of the
channel. This continued until the current met the resistance
offered by breakwaters constructed by Mr. Jeff. Thompson thirteen years ago, and still remaining effective along the east bank.
It was then where it was wanted.
"I have said the pockets disappeared after passing below the
end of Beard's dike. The river there was thirty-five hundred
feet wide, while at the bridge it is but fourteen nundred, with
the width in which it was possible to scour narrowed by Weaver's
dike to less than eleven hundred, and in this space stood a pier
twelve feet, and a draw-rest thirty feet wide. The great quantity of sand taken away by the river above Beard's dike must,
therefore, be deposited in the still water behind it, or be carried
through the narrower space at the bridge. For some weeks after
the flood was at 93 the channel below Beard's dike was very
uncertain.  Every pocket that came down from  above made
changes in the direction of the current, which sometimes struggled over the lower end of the bar and through the bridge, and
again rushed westward over Weaver's dike to the west shore.
The amount of sand brought down was more than it could at
once dispose of, and a sand gorge formed opposite Weaver's
dike, which changed the slope of the river in half a mile from
five inches to nine. Thus the whole channel was caught in a
great pocket, with Weaver's dike on one side, the clay banks on
the other, and a sand gorge at the bridge in front. This gorge
disappeared wholly about four weeks after the formation of the
great pocket, and the channel became uniform and along the
east bank of the river. The line between the still water above
Weaver's and below Beard's dike and the current became defined; the sand deposits along this line began; and, at this writing, with the water at 87, the west boundary of the channel is
as regular as the east, and is defined by a bar out of water
nearly all the way from a mile above Beard's dike to the bridge.
" Whenever the surface current was forced over Weaver's dike
by the sand gorges in the channel, the direction taken approximated to a line at right angles with the dike; therefore it impinged upon the west bank immediately in the rear of the dike,
The effect of this impingement was to form whirlpools about two
hundred feet in diameter between the dike and the bank, the
outer rim running at the rate of ten miles per hour, the vortex
two to two and a half feet lower than the rim.  These whirlpools often developed themselves fully in fifteeen minutes from
their beginning, and would cut away the bank at the rate of




19
thirty feet in twenty minutes.  They often became in half an
hour so full of driftwood that the water was scarcely visible.
Their action upon the bank was stopped by a revetment of trees,
brush and riprap, followed by a double line of piles driven parallel with the shore, and about a hundred feet from it. When
the sand gorges in the channel gave way, these whirlpools ceased
as quickly as they began, and the driftwood floated away down
the river. Soundings taken over the space where they existed
immediately after their disappearance, showed that they scoured
to the surface of the clay stratum  at an elevation of 45.  The
dike remains as it was built.  Had Weaver's dike been placed
at right angles with the current, these whirlpools could not have
formed; and in completing the system of dikes at the west
approach, the bank of the approach will be made the high-water
dike, and a low-water dike will be built to 82 directly along the
bridge line, six hundred feet out from the west abutment, thereby leaving Weaver's dike to act simply as a revetment for the
west shore above the bridge.
"The influence of Beard's dike is such that for a mile above
it, and west of a line parallel to the present channel and passing five hundred feet to the east of it, there is no channel with
the water at 87 for a boat drawing three feet; while in many
places, and particularly in the deepest of the channels obstructed
by it, the sand has filled in forty feet deep, and now completely
covers the dike from sight.  The surface of the new  bar is in
many places at 94. Below the dike, sand and mud have been
deposited, so that with the river at 82 there will be a bar a mile
and a half long and half a mile wide, where flowed the river
eight months ago. The amount of deposits caused by this dike
during the flood of this summer (1872) is more than 8,000,000 cubic
yards.  The bulk of the dike as it now  stands is 56,000 cubic
yards, of which 3,000 cubic yards is riprap, and the rest brush
and trees, with the interstics filled with sand. Its cost, including
engineering and superintendence, was $32,600, and it was built
in four months time.
"Weaver's dike was built at right angles to the line it was
expected the current would take after being disturbed by Beard's
dike, and for the purpose of resisting the current until Beard's
dike should have caused the channel to run along the east shore,
and entirely away from it. Had it been built perpendicular to
the channel at the time it was commenced, it would have failed
to protect the shore, as the new channel would have run parallel with it.
"It was not expected that one flood would accomplish all that
was desired, but the extraordinary duration of the flood this summer-about 90 for ten weeks-enabled the river to do as much




20
as was expected of it in two ordinary seasons.  I think more
water has passed this summer than during the great flood of
1844, which, although six feet higher than the river has been
this year, was of short duration. The water now averages four
feet above that at the same time in any year of which we have
any record; and it is still so high above low-water that the
whole effect of the works cannot be seen with the eye, but is
only known by careful soundings.
"I have endeavored in this paper to state as briefly as possible, the purpose for which the works were built, the surrounding circumstances, and the results already attained; and although
in my own mind I am satisfied that our success is complete, I
purposely avoid suggesting theories or drawing conclusicns until
the present flood shall have subsided and shown exactly what
has been accomplished.
"September 1st, 1872."
S;ince the above was written, nearly a year has gone by.
When the high water of 1872 had fairly passed, it was
evident that the dikes had fulfilled their purpose. More was
accomplished than even the most sanguine had dared to hope.
The river had been moved bodily more than half' a mile to
the eastward. The long, wide sand-bar that had interposed
between the city of St. Joseph and the river, had entirely
disappeared, and its place was now occupied by the main
channel; and on the opposite side, where the river formerly
ran, was now dry ground.
The full channel of the stream:low flowed immediately
in front of the city, passing squarely through the openings to
be spanned by the proposed draw.
By the comparatively insignificant dikes the mighty power
of the river itself had been placed in harness. The boiling
waters had dug their own channel exactly as desired, and
flowed obedient to the will of their master.
The winter of 1872-3 has now passed, and also the flood
of the summer of 1873; and the course of the stream still
remains unchanged. The principal structure, being the one
spoken of in the foregoing paper of Col. Mason as "Beard's




21
dike," originally built out from  the Kansas shore, directly
into the main channel of the river, now forms the spine ot a
great sand-bar.
Thus, by careful and intelligent conformity to the laws of
nature, can the greatest results be accomplished by the sitnplest agencies.
January 15, 1872, the second Board of Directors were designated, and consisted of
WILLARD P. HALL,        V. Z. RANSOM,         J. D. MCNEELY,
PETER G. CONT ISK,      G. IH. KOCH,         ROBT. GUNN,
JEFF. CHANDLER.        JOHN PINGER,          J. L. BITTINGER,
FRED. W. SMITH,        T. B. WEAKLEY,        R. H. JORDAN,
S. P. HYDE,
all of St. Joseph.  At their first meeting they proceeded
to the election of officers by ballot, with the following result:
President.-Willard P. Hall.
Vice-President.-Jeff:  Chandler.
Treasurer.'G. H. Koch.
Secretary.-Robert Gunn.
Auditor.-John L. Bittinger.
Superintendent and JEnrgimneer.-Ed. D. Mason.
Februarv 11th, 1873, the stockholders met at their office,
and selected the following gentlemen Directors for the ensuing year:
WILLARD P. HALL,        W. B. JOHNSON,         I. G. KAPPNER,
JAMES MCCORD,           G. H. KOCH,            W. M. WYETH,
MILTON TOOTLE,          ED. D. MASON,          ROBERT GUNN,
J. D. MCNEELY,          JEFF. CHANDLER         LOUIS HAX,
R. L. MCDONALD.
The new Board met on the 14th and elected tile following
officers:
President. -Willard P. Hall.
Vice-President -Jeff. Chandler.
Secretary. —Robert Gunn.
Treasurer.-G. H. Koch.
Chief Engineer and Superintendent.-Ed. D. Mason.
Auditor.-J. L: Bittinger.




THE SUBSTRUCTURE.
There are six piers which are identified by their numbers
respectively, beginning with No. I. on the Missouri shore, and
ending with No. VI. on the Kansas shore: No. II. being the
pivot pier for the draw span. In addition to these, there are
two structures, one above and one belbw the pivot pier, which
serve as rests for the ends of the draw span when thrown
open for the passage of boats.
The piers proper are of masonry, founded upon heavy tim-.ber caissons, which are placed in every case solidly upon the
bed-rock. The draw-rests are substantial timber cribs sunk to
the rock, and filled with rubble stone. Between the drawrests and the pivot pier are heavy frames of timber, which
float upon the surface of the water, guided by grooves prepared for that purpose in the masonry, These floats are of
sufficient strength and width to ward off from the bridge,
when open, any possible blows from boats.  They also act as
guides for steamboats in passing through the draw openings.
The process by which the piers were sunk to the bed-rock,
is described in the following article, being a paper prepared
by Mr. Willard S. Pope, President and Engineer of the
Detroit Bridge and Iron Works, the contractor for both substructure and superstructure, and read by him April 8th, 1872,
before the Civil Engineers' Club of the North-West, at Chicago.
" A bridge is now being constructed over the Missouri river at St.
Joseph, Mo. The work is under the general direction of Col. E. D.
Mason, as Chief Engineer, the Detroit Bridge and Iron Works of
Detroit, Mich., being the contractor for the entire job.
"The structure when complete will consist, as at present designed,




23
of three fixed spans of 300 feet each, and one pivot draw-span of 365
feet, and one fixed span of 80 feet, making a total length of 1,345 feet.
The superstructure will be of iron throughout, with floor arranged for
both railway and highway traffic. The substructure consists of piers
of masonry sunk to the bed-rock.
"The object of the present paper is to describe the plan of the
ordinary river piers, and the method adopted for sinking them.
"The necessity of placing the piers fairly upon the bed-rock is
sufficiently apparent to every one at all familiar with the character of
the Missouri river.
"The difference in elevation between high and low water at St.
Joseph, is about 22 feet. Borings on the line of the bridge show the
bed-rock to lie quite uniformly level at a depth of about 67 feet below
high water, or say 45 feet below low water line. During the stage of
low water, the main channel of the river at the bridge site has, during
the past season, hugged the east bank. Here for a width of say 400
feet' the water is from 15 to 25 feet deep, running with a velocity of
about three miles per hour. West of this it shoals rapidly up until the
sandy bottom appears. The depth of water at the different piers as
located has been during the past six months about as follows:
Pier No.  I.,..say 8 feet.
"    II., draw pier,.......           " 25  "
"   III.,....               " 12'
"   IV.,.. "  6"
~    V,............    t
VI................    on the bar.
" It is perhaps unnecessary to say that the above only indicates
the present profile, for the bed of the river is changing constantlythe only certainty being uncertainty-the only stability being utter
instability. The Missouri is a very cat among rivers-sly, treacherous, false, cruel. The only way to treat it is always to suspect it;
always to be armed and vigilant against it.
" Operations were begun on the west side of the river. A large
and convenient yard for stone, timber, etc., was provided and liberally
arranged with tracks, travellers, etc. From the west bank a pile
bridge was built across the bar out into the river so far as to the location of pier IV., a distance of about 760 feet. On this bridge tracks
were laid so that all material could be carried in cars directly to the
desired locality. The permanence of this bridge, during ordinary
water, was secured by an extensive dike of brush, earth and stone,
built out into the river just above it at such an angle as to deflect the
current to the opposite side of the river, and away from our works.
" The general plan adopted for sinking the piers was that of undermining them by excavating the material, uniformly and intelligently, from beneath them, and thus lowering them by their own weight




24
gradually and constantly to their desired final resting place. Workmen were to be continually operating beneath them, the possibility of
their presence there being assured by an air-pressure which should
entirely force out the water from a chamber at the base of the pier.
"This, then, indicated the general form of the bottom of the pier.
It should be an inverted caisson, inclosing an open space or chamber
sufficiently large for all the operations of the workmen.
"The caisson for pier IV. was constructed as follows, this being
one of the ordinary-sized river piers, which are 9 feet wide and 20
feet long under the coping at the bridge seat:
" Tile exterior dimensions of this caisson at the bottom are 24 feet
wide and 56 feet long, with rectangular corners. The sides and ends
batter from the bottom toward each other in the ratio of one horizontal to twelve vertical. The caisson is constructed of 12 x 12 inch hard
wood timber throughout, and is divided into two parts-the caisson
proper, being that part which incloses the inner working chamber,
and the grillage or platform of timber interposed between the roof of
this chamber and the bottom of the masonry. The caisson proper is
say 13 feet high and the grillage 7 feet high, making a total height of
20 feet from the bottom of the caisson to the bottom of the masonry.
"The caisson proper consists, first, of an outer course or skin of
timbers placed side by side vertically; second, an intermediate course
of timbers placed side by side horizontally; and third, an inner course
of timbers placed side by side vertically.  Thus the walls of the
caisson are of solid timber three feet thick. The bottom of the inner
course stops one foot short of the bottom of the intermediate course,
while that in its turn stops one foot short of the bottom of the exterior course. One foot above the bottom of the inner course is placed a
longitudinal timber girt, running entirely around the interior walls of
the caisson. On this girt rest the ends of a continuous course of
inclined timbers, sloping upward and inward at an angle of about
forty-five degrees. and connected together at their tops by a continuous course of straining beams forming the roof of the chamber.
" Thus it will be seen that the inclosed space at the base of the
caisson is a floorless chamber about 22 feet wide and 54 feet long at
the bottom, sloping up on all sides, until at the top it is reduced to a
width of 5 feet and a length of 37 feet, the height being about 9
feet. Running across this chamber at the level of the horizontal girt,
about 4 feet from the bottom and at intervals of about 8 feet,
are timber struts and iron tie-rods, so arranged as to be capable of
adjustment within the chamber.
" The triangular space all around the caisson, between the exterior
3-feet walls and the sloping interior rafters, is filled with concrete
carefully packed. Over all, resting upon and framed into the exterior walls and the straining beams, and thoroughly bedded in the concrete, are placed three solid horizontal courses of timber alternating




25
in direction, thus making the roof of the chamber four feet of solid
timber in thickness. Upon the top of this is the grillage, a system of
seven horizontal courses of timber, each course laid at right angles
with the one below it. These timbers in each course are spaced six
inches apart, except the final or top course, which is solid. The grillage and the caisson together make up a total height, as before stated,
of 20 feet.
"While the caisson proper is, as above described, rectangular in
horizontal section, the grillage is gradually drawn in, so that at the
top it corresponds with the general shape of the masonry of the pier,
which shows a curved starling at each end.
"All joints and beds in the timber work are carefully and accurately fitted, great pains being taken with the joiner work; and the
whole is very securely and thoroughly bolted, together, forming as far
as possible a single, solid, stiff and homogeneous mass, capable of
resisting strains in every direction.
"The interior of the air chamber is very carefully caullked, so as
to be as far as practicable absolutely air-tight.
" The peculiar arrangement of the bottom bearing surface will be
observed. The exterior course of timber descends the lowest, and so
exposes for the cutting edge an area equal to the entire perimeter of
the bottom of the caisson, and one foot wide. Where clay or boulders are expected, this cutting edge is hewed to an angle, and well
shod with plate iron.  After this is buried one foot in the sand,
another bearing surface comes into use, being the bottom of the intermediate course of timber; and after this in its turn has descended
one foot, the bottom of the third or inner course of timber is ready
for service; and, again, after another foot comes the horizontal girt.
Thus the amount of bearing surface to be brought into requisition is
entirely at the option of the workmen in the caisson. Should the
material be soft and the caisson descend too rapidly under the accumulating weight of the masonry, the more it descends the broader
becomes the area of support, and so the difficulty remedies itself.
Should the material be hard and obdurate, or should snags or other
obstructions be met with, the exterior cutting edge itself can be
exposed, or, if necessary, the men can work entirely under it and so
get at and remove the obstruc.tion. Should the material be unequal,
one side soft and the other side hard, the bearing surface on the former can be increased, and on the latter diminished, at will.
"Hanging from the middle of the roof of the air-chamber is the
air-lock, a hollow, closed cylinder of plate iron four feet in diameter
and seven feet long. Tn one side is a door opening outward into the
air-chamber, and in the top is another door, opening inward into the
air-lock. From the top of the air-lock ascends the air-shaft, an open
cylinder of plate iron three feet in diameter, reaching to the upper
4




26
air, a suitable hole being left for its passage through the roof of the
caisson, the grillage and the masonry. An iron ladder allows easy
access through the shaft to the air-lock.
" Through the roof of the caisson, the grillage and the stone work,
pass the necessary air and water pipes connecting the air-chamber
with the pumping machinery outside.
" The caisson is placed in position and lowered down until it
reaches the sandy bottom. Air is now pumped into the chamber,
which gradually displaces the water, driving it out under the bottom
until it is entirely full of air and empty of water. The workmen can
then descend the air-shaft into the air-lock, which is large enough to
hold six men at one time. Closing the door above their heads communicating with the air-shaft, a cock is opened which admits into
the air-lock the compressed air from -the air-chamber; until presently
when the pressure in the air-lock is equal to that in the air-chamber,
the door connecting the two can be opened, and the men step through
into the chamber upon the sandy bed of the river. The passage out
is, of course, by reversing the process.
"A small pipe leads from the air-chamber up through the airshaft, at the top of which is an ordinary steam whistle. The compressed air from the chamber, when admitted into this pipe, blows
the whistle; and by this means a complete and easily understood
system of signals is arranged between the men within and without
the chamber.
" And now begins the work of settling the mass. The material in
the chamber and under the bearing surfaces of the caisson must be
excavated and removed. As this is done, the pier gradually and certainly descends by its own gravity.
" Formerly, and still in many places, this work of excavation was
done by hand, the sand being packed into bags or buckets and hoisted laboriously through the air-lock. This process, while it may answer for small pipes or cylinders, is too slow and tedious for such large
caissons. The cubic contents of a mass the size of the bottom of one
of the ordinary river piers at St. Joseph, reaching from the rock up
to the water line, is not less than 2,200 cubic yards. All this material
is to be removed, that its former position may be occupied by the
pier. In addition to this, large quantities of sand from without the
chamber are often sucked into it by slides under the cutting edge, and
must be removed.  Doubtless in practice not less than 3,500 cubic
yards, and very likely more, must be excavated to settle one of our
piers. To move this mass, raising it an average of say 40 feet in
height, the inefficiency of bags and buckets hoisted through the airlock, is palpable.
" We use for this work the sand pump, as devised and adopted by
Capt. James B. Eads for his great work, the St. Louis Bridge. I




27
desire here to express my acknowledgements to this eminent and
successful engineer, for the warm, friendly interest he has taken in
our work at St. Joseph. The valuable results of his extended experience at St. Louis have been freely communicated and his advice has
been of much service.
"The sand-pump above referred to is somewhat similar in its
mode of action to the well-known Giffard injector.  Its general
description and modus operandi with us is as follows:
" On a boat or platform near the pier is placed one of the largest
sized Cameron water-pumps. This is a direct-acting engine with a
steam cylinder 18 inches in diameter, and a water cylinder 12 inches
in diameter-both 36 inches stroke. This, running at a speed of 20
full strokes per minute, delivers water at the rate of 760 gallons per
minute. The water thus delivered is carried through a 5-inch pipe
down into the air-chamber, whence it is returned through a 3-inch
pipe enlarged in its upper portion to 4 inches, and so discharged over
the top of the pier. At the point of discharge into the smaller pipe,
and within the air-chamber, all the water passes through an annular
opening about 21- inches in diameter and perhaps I inch wide. It is
evident that to pass so much water as is delivered by the pump,
through a 4-inch pipe (a sectional area of 121 square inches), it must
move with great velocity.  But at the point where it is forced
through this annular opening (a sectional area of not to exceed one
square inch) its velocity must be enormous. Indeed, the struggle of
the water to squeeze itself through this narrow passage-way produces
a pressure at the pump and in the pipes of about 150. pounds per
square inch. The interior space of this annular opening is the upper
end of a suction pipe, in which it is evident that the velocity of the
water must create an almost perfect vacuum. The other end of the
flexible suction hose is held to the sand, which is stirred up and
moistened by a jet of water directed against it from a nozzle in the
hands of one of the workmen. The power of suction is of course
increased to the full extent of the air-pressure in the chamber; and
the result of the combined action of the powerfil water-pump and
the air pressure is a constant and, in free working material, an astonishingly profuse discharge. Sand and gravel seem to absolutely melt
and instantly disappear at the magic touch of the end of the suction
pipe. The discharge from the escape pipe over the top of the pier, is
water so thick with san —d or silt as to be almlost viscid. I have never
carefully gauged the capacity of one of these wonderful little instruments, but I presume that under favorable conditions it will deliver
between 40 and 50 cubic yards of sand per hour.
" At St. Joe, thus far, the great bulk of the material to be excavated has been sand or silt of such a nature as to work freely through
the pumps. Still, we have met much clay and considerable deposits




28
of medium-sized boulders, which were necessarily hoisted through
the air-lock.
"In the ordinary small caissons, as above described, we place two
sand-pumps, either or both of which can be run. In the larger caissons we shall place four pumps, with a power to work three at a time
if necessary. To drive three sand-pumps satisfactorily requires an
engine capacity of about 300-horse power.
"Our pneumatic plant consists of six blowing cylinders driven by
four steam engines, aggregating about 300-horse power, nominal,
with a united capacity of discharging about 1,700 cubic feet of air per
minute, under a pressure say 20 pounds per square inch. Two blowing cylinders coupled together constitute a battery and each battery
can be and is worked independently of the others. Generally only
one battery at a time is required for a caisson-the others being run
elsewhere or held in reserve.
"To furnish steam for this machinery, are required seven large
flue boilers and one tubular boiler.
"For derricks and the various demands of the work there are in
use six portable engines. Thirteen considerable barges, with quite a
fleet of small boats, are engaged in the service.
"The masonry is built upon the caisson as it descends, the top of
the pier being always above.water. Thus there is always ready a
surplus of weight necessary to sink the pier. By reason of this surplus no exact estimate has been made for the coefficient of the friction of the sand upon the sides. During the earlier stages of sinking
and at small.depths, the nmass slowly and constantly descends as the
material is excavated from beneath it. As greater depths are reached and the friction of the surrounding material upon the immersed
area becomes considerable, it moves with more reluctance. The process now is to remove the sand nearly or quite to the cutting edge
and, in extreme cases, even below it; and then, after sounding carefully under all sides, to be sure that there is no concealed snag or
other obstruction to the downward passage, the air pressure is relieved as far as may be necessary. Presently the mass seems to be a
living thing. It groans, trembles, quivers, seems to shake itself free
from its shackles, and fairly lurches downward in a series of rapidly
consecutive and convulsive spasms, until its descent is gradually
stopped by the increased bearing surface at bottom brought into
action by its own motion. Sometimes in this way it will go down
two feet in as many minutes.
"'The work of sinking is prosecuted continuously. The caisson
men are divided into three watches of eight hours each, until a depth
of 35 feet or so is reached, when the increasing pressure renders it
desirable to shorten the watch to six hours, and at greater depths the
hours of duty are still further diminished.




29
"In free-working material we have frequently made 5~ feet, and
occasionally even 7 feet in 24 hours. ()ur general daily average however, will probably fall a little short of two feet.
"The air-pressure, of course, varies with the depth of water, a
column of water one foot high and one inch in section balancing
somewhat less than one-half pound per square inch of pressure. The
depth of the rock thus far has been about 50 feet below ordinary water
surface, requiring a pressure above that of the ordinary atmosphere
of about 23 pounds per square inch. No serious incohvenience has
thus far been experienced by any who have been subjected to it.
" When the rock-bed is fairly reached, a wall of concrete is built
under all the bearing edges of the caisson. This wall is about six
feet wide on the rock, and is brought up in layers and carefully and
solidly rammed under all the bearing timbers up to and including the
horizontal girt mentioned above in the description of the caisson.
The air-lock, air-shaft, and air-pipes are then removed, the operation
of the sand-pumps reversed, and clean sand, and gravel are pumped
with great force into the chamber. The accompanying water, being
lighter than the sand, is expelled through a pipe left for the purpose,
and thus the chamber is filled compactly and thoroughly. In this
way the entire horizontal area of the roof and of the sloping sides is
made available for bearing surface. This is assumed to be as reliable
a bearinll as masonry itself, inasmuch as the concreting at the bottom of the caisson renders the escape of the sand impossible, even
should the material surrounding the caisson be scoured to the rock
itself.
" In addition to this, vertical posts of heavy timber are placed with
their feet bearing on the bed-rock and their tops solidly wedged under
the roof of the air-chamber. A permanent support can thus be
obtained to the entire extent of the area of the caisson, if it is desired.
" The sand pipes are then unscrewed and withdrawn, the openings for the various pipes and shafts filled up, and the pier finished.
" The caisson for one of the ordinary piers for this bridge contains
about 185,000 feet, board measure, of hard-wood timber, about ten
tons of iron bolts, etc., and abcut 120 cubic yards of concrete in the
hips and under the cutting edges. The pier proper contains about
1,000 cubic yards of masonry. From the bed-rock to the bridge-seat
of pier is about 77 feet.
" The material through which the piers have passed is, as has
been already mentioned, mainly fine sandi or a species of silt peculiar to this river. Frequent pockets and often regular. strata of stiff,
hard clay (known in that country as "gumbo") have been met.
Snags And drift are of frequent occurrence. At a depth of 40 feet,
pieces of brick and fragments of coal have been taken out, showing
that in comparatively recent times the scour has reached that depth.




30
The bed-rock has been generally immediately overlaid with a deposit
of from two to five feet of medium-sized boulders mixed with very
coarse sand.  These boulders are all thoroughly water-worn and
rounded by attrition, and have evidently been brought from great
distances at some remote period of the history of that region. They
are of red and gray granites, schist, gneiss, conglomerate, trap,
quartz. Many agates have been found, some amethysts, many small
rubies, and many specimens-some fine ones -of gold-bearing
quartz. The bed-rock is a smooth, hard, whitish-gray limestone,
overlaid with a broken shale of two or three inches in thickness, but
underneath this, very solid and reliable.' The water in the Missouri river is generally very much discolored-indeed, fairly turbid-with the quantity of earth and sand held
in solution. But the water found percolating through this deposit of
boulders over the bed-rock is as pure and clear as that from any
mountain spring. While ice at the surface was two feet thick, and
the mercury often many degrees below zero, this water had a uniform temperature of 54 degrees Fahrenheit.
" This description, long as it is, would not be complete were I to
neglect the expression of my satisfaction with the certainty, celerity,
and comparative ec:onomy of the pneumatic process, as adapted for
deep-water foundations in localities similar to this. True, it requires
a large, complete, powerful and very expensive plant; but, with that
provided, one of these massive piers can be handled with an ease and
a security that is unknown to any other system with which I am
familiar. For instance, by an accident, one of our caissons was
landed upon the sand two feet too far south and two feet too far east,
but during the sinking we worked it back to its true position without
difficulty. All through the severities of the past unexampled winter
the work of sinking has gone forward almost without reference to
the weather. When, by reason of storm and cold, men could not
work out of doors, the labor in the warm, sheltered air-chamber has
been almost uninterrupted.
" Detroit, March 30th, 1872."
The first pier takeln in hand was _No. VI. Then came No.
V., which was immediately followed by No. IV.  At the time
the caissons for these three piers were placed in position fbi;
sinking, their location was in quite shallow water.  It was at
a season of the year when floods were not to be expected. The
caissons were therefore built i&n sitg, supported upon piles,
their bottom  being placed at an elevation of two or three feet




31
above the water. After being put together, they were lowered
down to the river bed.
The process of lowering was to cut off the piles, supporting
the caisson meanwhile upon blocking piled up "cob-house
fashion."  After the piles were all cut off; a strong water jet
judiciously directed against the sand under the blocking gradually undermined it, and so the heavy caisson descended gently
and easily until it reached the sand,
A somewhat singular accident occurred during the process
of lowering the caisson for pier IV. The piles were being
removed, and the caisson stood partly on piles and partly on
blocking. A  sudden sharp whirl of the current struck the
blocking, undermining it, and in the night the caisson fell
heavily downward about nine feet, to the bed of the river.
Much anxiety was felt, but when daylight arrived and an
examination could be made, it was found to be entir6ly uninjured and to be right side up, in almost exactly the right position for sinking. Thus an accident fortunately accomplished
in a moment, what would have taken several days of hard and
careful work.
The next pier undertaken was the upper draw-rest. This
was in the deep and swift water of mid-channel. The caisson
was therefore suspended by large screws between two barges,
and when all was ready was lowered to the bottom by the
screws. The same plan was adopted with the caisson for pier
II.
The location of pier III. was debatable ground; one day a
dry sand-bar, and the next deep water. Therefore this caisson
could not be placed upon boats. A frame-work of long, heavy
piles was very thoroughly driven about the site of the pier,
and the caisson suspended by screws from this platform. At
the time the piles were driven, there was less than two feet of




32
water; but before the caisson was ready to be lowered, scour
had taken place, so that the water was nearly 30 feet deep.
As may be imagined, this state of things rendered the platform very insecure. Great promptness and much hard work
alone saved it, and when finally the caisson was safely landed
on the sand, every one experienced great relief.
The caisson for pier I. was built on the east shore and
launched into the water, and so placed in position.
During the process of sinking pier II., one of the pumping
barges sprung a leak in one of its compartments, and before
it could be stopped, the boat capsized and sunk in about 30
feet of water, carrying with it to the bottom all its load of valuable machinery. Duplicate boats and engines were ready
however, so that the accident did not involve an hour's delay
of the work.
As soon as the necessary preparations could be made, an
air pipe was led into the hold of the sunken barge, and air
pumped into it, expelling the water. This inflation bouyed it
up so that it rose to the surface of th.e water. While it lay in
this condition, its bottom just above the water, it was thoroughly caulked and repaired.  It was then slung under the trusses
which had been used for suspending the caisson of pier II.,
and by the use of the screws was turned over right side up.
The engines and pumps, which when originally placed in position had been firmly bolted to the deck, were found to be
still fastened thereto, and except for their submersion in the
muddy water, were uninjured. The boilers however still lay
at the bottom of the river. They were notwithstanding subsequently recovered.




33
DIMENSIONS OF PIERS,
No. of Pier.     Size at Top.     Size at Bottom.    He Rockight from BedI.                    8ft. x 25ft.  22f. 6i. x 38f.6i.  71ft.
II.  - -          33ft.2in.Diamn.      45f. x 45f.       71ft.4in.
III.  -  - - -          10ft x 25ft.  25f.6i. x 56f.8i.   75ft.4in.
IV.  -              9ft. lin. x 25ft.  24f.4i. x 53f.3i.  75ft.3in,
V.  -              9ft.lin. x 25ft.   24f. x 56f.       73ft.
VI.  -                  8ft. x 25ft.  24f.4i. x 38.f.4i.  71ft.
Upper Draw Rest        25ft. x 27ft.    38f. x 58f.       73ft.
Lower Draw Rest        26ft. x 26ft.    31f. x 31f.       73ft.
IMATERIAL IN PIERS.
No. of Piers.       Ft. B. M.   Lbs.   Cub. y'ds Cub. y'ds Cub. y'ds
No. hof Piers.  Timber.   Iron.   Concrete.  Riprap.  Masonry.
East Abutment,  - - -           ------             30                 48
Pie' N'o. I.,     -       - -  129,000  17,000     83                773
II., - - - - -    345,000  47,000          95     _ _      1,913
III. - - - - -     199,000  27,000    108                     1,142
IV., - - - - -    175,000  27,000    134                     954
V., - - -  - -   142,000  22,000    135                     933
"  VI., -  - -           116,000  16,000       75                629
Upper Draw Rest,   - -   380,000  48,000    105    2,000
Lower        "        - -   125,000  14,000  ----    1,000
Floats,   -  - - - - -         61,000  24,(100            ~ - 
Tota,  - - - -  1,672,0001 242,000 1  765    3,000    6,392
The following is the general specification  for the  masonry  as e" mbodied  in  thle  contract  with  the  Detroit Bridge
and  Iroll Work.
MASONRY,
" STONE.-The work will consist of sound, durable lime, magnesian
lime, or sandstone, from  such quarries as may be accepted by
the Chief Engineer, ailj  shall be free from shaqkes, dry cracks,
or other irnperfections..
5




34
" ASHLAR —BACKING —CONCIRETE-COURSES TO BE LEVELED UP-SIZES
OF COURSEs —The exterior of the abutments and piers shall be
rock-faced ashlar, pitched to the batter shown by the drawings,
cut on the beds and joints and backed with sound stone, fitted
close to place and laid in full beds of mortar. The backing
or filling of the piers may, however, consist of concrete, made according to the specifications for the same, each course to be
fully completed and leveled before the commencement of another. At least one-third of the stone shall be over eighteen
(18) inches in height, one-third from fourteen (14) to sixteen (16)
inches, and not to exceed one-third twelve (12) inches.
"STONES TO BE ON NATURAL BED-BEDS AND JOINTS-VERTICAiL
JOINTS - HEADERS - STARLINGS - DOWVELLING - BOND. —A11
stones shall be cut to lie on their natural beds, which are to be
dressed square and true throughout to a three-eighths (8) inch
joint. The width of all beds shall be at least one-half greater
than the height of the course, and vertical joints shall be dressed
square for a distance of nine inches from the face. There shall
be headers in each course-one for every two stretchers-two
feet and a half'long, In the face of the piers; starlings to be
formed of three stones, as shown on plan. The courses of stone
laid in the upper and lower starlings and shoulders shall be
dowelled together as follows: Through each stone, after being
laid, a hole shall be drilled and continued five inches into the
stone beneath; a dowel of round iron, ten inches in length and
one inch diameter, shall be inserted, and the interstice
filled with grout. All courses shall break joints with each
other not less than one foot.
" STARLINGS TO BE BUSH-HAMMERED-DRAFT LINE TWO INCHES.
-In addition to the cutting of beds and joints, the whole upper
face of starlings between high and low water shall be bushhammered; also copings of piers and the grooves in the pivot
pier for floats. On all piers there shall be a margin draft two
inches wide, chiseled on angles, and string courses, and the
courses and copings of wing walls of abutments shall be cut
according to detailed plan.' COPING OF PIVOT PIER.-Coping shall be sixteen inches thick.
The coping of bridge seats shall be long enough to cover the
whole width of 1tli s, and the coping of pivot pier shall extend
unbroken at least four feet from the face, and shall be fitted to
place so that adjacent stones shall break joints at least one foot
"MOORING RINGS.-Two rings, made of one and a quarter inch
round iron and six inches clear diameter shall be firmly secured
in the down stream end of each pier.
"ANGLE IRONS.-On the point of the upper starling of each pier




35
there shall be bolted an angle iron in a single piece, long enough
to extend from below low water to the string course, four
inches wide on each face and one half inch thick, and firmly
secured to the pier by a wedge or bolt at each joint in the
masonry.
" MORTAR-HOW PROPORTIONED-CEMENT TO BE APPROVED OF BY
ENGINEER.-The mortar shall consist of one-half hydraulic
cement'of such brand as may be accepted by the Chief Engineer, and one-half clean, sharp, river sand.
"POINTING.-The whole work exposed to view shall have the joints
picked out and pointed with a tool.
CONCRETE.
"How PROPORTIONED.-The concrete shall consist of two cubic
yards of limestone, broken so as to pass through a two and a
half inch ring, and screened, three and a half barrels of cement,
as aforesaid, and three and a half barrels coarse, river sand, the
whole to be mixed by spreading the sand on a layer of the stone,
and the cement on the sand, pouring on water, with a common
watering pot, and thoroughly turning the whole over till each
stone is covere. with mortar. All concrete made must be used
immediately. That put in for foundations of abutments must be
laid in about eighteen inch courses, and each course thoroughly
rammed while fresh.
" To BE FRESH GROUND-CEIVIENT CONDEMNED TO BE DESTROYED.All cement used shall be fresh. ground and subject to frequent inspection, and alny that may, from any test applied, be found to
be of inferior quality and condemned, shall be destroyed immediately."




THE SUPERSTRUCTURE.
The Material Used, and How the Bridge was Built.
The bridge is divided into spans as follows, beginning at
the abutment on the east side of the river: one fixed span
80 feet long, one pivot draw span 365 feet long, three fixed spans 300 feet long each, making a total of 1345 feet between the abutments on either side of the river. Each span is
carried by two trusses placed 20 feet apart between centers,
and carrying between them a flooring for a railway and waggon way 18 feet wide in the clear. The floor-beams project
beyond the trusses on each side for the support of foot walks
four feet wide each in the clear.
The bridge is built of wrought-iron throughout, except the
upper chords of the 300 feet spans, and except the tracks,
wheels, &c., of the turntable under the pivot draw-span, which
are of cast iron.  The tension rnetmbers are forged eye-bars of
the required number and dimensions, varying from 1T inches
to 3 inches in diameter, and from 2 by 2 to 61 by 2 inches.
The compression members are of heavy rolled beams of
wrought iron, of such shapes and sizes as to best subserve the
purposes for which they are designed.  Every piece of iron is
so formed and used that its entire surface is accessible at all
times to the paint brush.
The general style of the structure is that known as the
quadrangular truss, with parallel chords and inclined tie-rods.
All the posts are vertical except those at the ends of each span




37
which incline over one panel. The lower chords, main and
counter tie-rods and the bolts sustaining the floor system, assemble at the foot of each post, and are there united by a
heavy forged pin.  The upper ends of the tie-rods pass
through the upper chords at the head of thle posts, and are drawn
up by nuts which bear upon bosses provided for that purpose.
The upper chords are in lengths of one panel each, and are
united together over the post heads by a tenon and socket
joint. They are of cast iron, octagonal in exterior section
with circular core. The diameter between the opposite parallel faces is 16 inches, and the thickness of metal varies in dif'
ferent panels to accord with the varying strains. Over each
post where the chord pieces join each other, they are swelled
to a width of 26 inches, thus affording room for the passage
through them of the various tie-rods. Suitable pockets and
bosses are provided for the reception of the upper lateral
struts and tie-rods.
The lateral struts consist each of two pieces of rolled
channel beatris 71 inches deep latticed together. The lateral tie-rods are of round iron varying from 1 inches to
14 inches in diameter.
The floor beams are of rolled I beams 15 inches deep
suspended in pairs from the pins at the foot of the posts.
The above description answers for the. long fixed spans.
These being placed permanently upon the masonry, the
nature of their loading is uniform in its character, and the
strains consequently vary only in intensity, not in character.  But in  the draw-span the strains are constantly
changing. When the draw is empty and swinging, one set
of strains is met, and when it is closed and loaded, another set, of directly the reverse nature, takes their place.
This of course necessitates a different form, both of material




38
and of construction. The chords, therefore, are continuous
throughout, and ot wrought iron, so designed in shape and
dimension as to resist strains of both tension and compression. The posts, struts, tie-rods and floor system are of
substantially  the same character as that above described
for the fixed spans.
The general characteristics of the various spans are as
follows:
EIGHTY FEET FIXED SPAN.
Two trusses, 8 feet high and 20 feet apart centres; 6
panels 13 feet 4 inches each.  Weight of span including
floor, 53 tons.
THREE HUNDRED ANIl  SIXTY-FIVE FEET DRAW SPAN.
Two trusses, 26 feiet high at ellnds and 34 feet highs at
centre; 20 feet apart centres; 2 centre panels 11 feet 2 inches
each, and 26 interior panels 13 feet each. Weight of span,
including flooring and turn-table, 440 tons.
THREE HUNDRED FEET FIXED) SPAN.
Two trusses, 28 feet 3 inches high and 20 feet apart centres;
21 panels 14 feet 11 inches each. Weight of each span,
including floor, 370 tons.
Total weight of bridge, completed, 1,603 tons.
About 20 feet above the floor over the turn-table of the
draw-bridge  an  iron  platform  is  fastened to the posts,
whereon is placed a steam engine with the necessary fixtures and attachments for turning the draw.  The engine
is double, and of about 20 horse power-of sufficient capacity to handle the bridge in any weather.
The following is the general specification for the iron
work, as embodied in the contract with the Detroit Bridge
and Iron Works:




39
SUPERSTRUCTURE.
" DEsCRIPTION.-The superstructure shall be of iron, similar in genleral plan and equal in character of workmanship and materials,
to the bridge over the Mississippi river at Hannibal.
"SPANS-HOW CONSTRUCTED.-The height of the girders shall be, for
the 300 feet spans, 28 feet 3 inches; for the draw span, 26 feet at
the ends, and 34 feet at the centre. The clear width shall be
18 feet between posts.
" CONTRACTORS TO FURNISH WORKING DRAWINGS.-Before construction is commenced, working drawiDgs shall be submitted to the
Chief Engineer of the Bridge Company for his approval.'"CAST IRON. All the spans shall be built entirely of cast and
wrought iron. The cast iron parts of the fixed spans may be the
upper chords, caps and pedestals of posts, bed plates and washers
of the draw spans, the caps and pedestals of posts and washers in
bridge; the center spider plates and stiffening pieces, wheels and
segments of turn-table, and track under same, and racks, pinions
and brackets for turning.
"WROUGHIT IRON-IRON TO BE TESTED —IRON TO BE REJECTED-A-LL
IRON TO BE FINALLY TESTED.-All other parts of all the spans
shall be of wrought iron. The wrought iron shall be of the best
quality, free from any imperfections affecting its strength. It
shall, before being used, be subject to thorough tests in a hydraulic press, and all lots from which any selected bars shall breAk
under a strain of fifty thousand (50,000) pounds to the square
inch shall be rejected. All the bars used in the Bridge shall be
subsequently tested to a strain of twenty thousand (20,000)
pounds to the square inch of section, and shall, while under tension, be struck with a hammer, and if any show permanent set,
or show signs of imperfect welding, they are to be rejected.
" MAXIM3UM TENSILE STRAIN ALLOWED ON WROUGHT IRON-MAXIMUMI COMPRESSIVE STRAIN —MAXIMUM STRAIN ON FLOOR BEAMS.
-The different parts of the structure shall be so proportioned that
a rolling load of two thousand five hundred (2,500) pounds to the
running foot,in addition to the weight of the structure itself,and the
track and flooring laid thereon,the latter estimated at six hundredl
(600) pounds per lineal foot, shall bring on no part a greater tensile
strain per square inch of sectional area than is shown in the following table, to wit: For parts which receive their full load
when the entire length of the span is loaded, 12,000 pounds. For
parts which receive their full load when three-fourths (3) of the
entire length of the span is loaded, 11,000 pounds. For parts
which receive their full load when one-half (~) of the entire
length of the span is loaded, 10,000 pounds. For parts which
receive their full load when one-fourth (4) of the entire length of




40
the span is loaded, 9,000 pounds. For single panel systems, 8,000
pounds. The factor of safety for compressive strains shall vary
similarly from four (4) to six (6) as calculated by " Gordon's formula;" and a weight of two thousand five hundred (2,500)
pounds per running foot shall in no case strain the floor beams
over eight thousand (8,000) pounds per square inch, calculated
upon the sectional area of the lower flange.
" WORKMANSHIP TO BE OF THE BEST QUALITY-UPPER CHORDS TO
BE CALLTPERED.-All the workmanship to be of the best quality.
The upper chords, if of cast iron, shall be callipered, and if found
to be one-eighth inch less than the required thickness of metal,
shall be rejected.
" GREATEST ERROR ALLOWED IN LENGTH OF BARS OR IN DIAMETER
OF HOLES-CONNECTING PINS TO BE TURNED.-The deviation
from a right line shall not exceed one-quarter inch to a twelve
(12) feet column. All abutting joints shall be planed or turned;
all pin holes in wrought iron shall be drilled. No bar of iron
having an error in length between the pin holes of over one thirty-second of an in6h, or in the diameter of the pill holes of over
one-hundredth of an inch, shall be allowed. All connecting
pins shall be turned, and no error of over one-hundredth of an
inch shall be allowed.
" IRON TO BE CLEANED AND PAINTED-MACHINE WORK TO BE PROTECTED.-All the iron work shall, as soon as possible after being
cleaned, be painted with one coat of oxyd of iron paint and oil.
All machine cut work, before leaving the shop, shall be covered
with a coat of white lead and tallow.' CAMBER.-The fixed spans shall be built to a camber of three (3)
inches. All spans shall return to the original camber without
readjustment after having been tested.
"TURN-TABLE-PLATFORM FOR.-The draw span shall be provided
with a turn-table of similar plan and equal in all respects to the
turn-table under the draw at H innibal. It shall be furnished
with turning gear, with friction wheels, to be turned by levers
and so constructed that two men shall be able to turn the draw
at right angles to the line in one and a half (12) minutes when
there is no wind blowing. The contractor shall also furnish a
steam engine, shafting and other attachments to imove and handle the draw, of similar construction and proportional power to
those in use at Quincy and Hannibal, also the platform on which
to place the same.
TRACK AND FLOORING OF BRIDGE.
" FLOOR-BEAMS-SCREW-BOLTS-IRON RAI LS-CARRIAGE TRACKS.Upon the floor beams shall be laid, for a railroad track, two pairs




41
of white pine stringers, free from black or rotten knots, shakes,
or any imperfections that affect durability or strength, and large
enough to size 7x16 inches after being planed; placed one-half
inch apart, with blocks or keys between, and long enough to
reach across two (2) panels, breaking joints, and secured by four
three-fourths (4) inch round screw bolts at each joint, or over
each floor-beam. In the center of each panel there shall be a
strut 3x12 with a three-fourths (4-) illch round bolt, having screw
and nut oil each end, and passing through both pairs of stringers.
The iron rails shall be of such form as may be hereafter -chosen
by the Engineer. The stringers, outside the track-stringers, shall
be four (4) in number, 6x14, and the ties shall be of oak 6x8,
eighteen (18) feet in length. and placed twenty-two (22) inches
apart between centers. The whole floor shall be planked with
two (2) layers of two (2) inch white or burr oak plank, laid as the
Engineer may direct. The roadway shall be protected by a
strong railing on each side.
"SIDE-WALKS.-A side-walk, four (4) feet wide in the clear, shall be
built outside the trusses on each side of the bridge; said sidewalks to be supported by the floor beams which shall project
for that purpose; to be floored with two (2) inch pine plank, and
provided with a railing upon the outer side.
PAINTING.
" PORTION OF BRIDGE TO BE PAINTED WVITH MINERAL PAINT-PORTION OF BRIDGE TO BE PAINTED WITH PURE WHITE LEAD.All the wood track stringers, iron floor-beams, lower lateral
rods, suspension bolts, washers, &c., shall be painted with two
coats of dark brown mineral paint, from the Brandon, Vermont,
works, mixed in linseed oil. All the rest of the iron work of the
bridge shall be painted with two coats of the best brand "' pure
white lead " and linseed oil, shaded to a drab color."
The various parts of the structure are so proportioned
that a moving load of 2500 pounds per lineal foot of bridge,
together with the weight of the, bridge itself, and the flooring, and  tracks thereon. shall bring on no part a greater
strain than one-fifth its ultimate capacity.  To illustrate:
A single 300 feet span weighs say 370 tons. The assumed
moving load (2500 lbs per foot) for the entire span amounts
to 375 tons; the sum  of both dead and live load is therefore 745 tons. The assumed breaking load of the bridge
6




42
is five times this or 3725  tons. The  assumed  live load,
viz: 375 tons, is considerably in excess of any real load
that can be  brought upon the bridge.  A  string of locomotives reaching from  end to end of the span will weigh
less than 300 tons, while an ordinary train drawn by one
engine and reaching entirely across the span will weigh
about 200 tons. Then it will be seen that the assumed
maximum  load is actually larger than can occur in practice. As a further assurance of safety, every bar of iron
in the bridge has already endured an actual tensile strain
sixty per cent greater than the imposition of the maximumn
load can bring upon  it in the finished bridge.  Before
leaving the works at Detroit, every bar of iron was placed
in the powerful hydraulic testing machine and there actually
subjected to a tensile strain sixty per cent greater than its
computed duty, and while under such actual stress received several sharp blows from  a hammer.  Any con
cealed flaw or imperfection in workmanship was very sure
to be revealed by this treatment. When to this it is added
that none but the best and toughest kind of iron is used,
and that the most scrupulous care is used in all the various
processes of manufacture, and that each part is so arranged
as to utilize its entire capacity, it may be fairly assumed
that ample strength has been provided.
In the science of bridge building there is absolutely no
guess work.  The strict deductions of mathematical logic
show  exactly the duty to be performed by every component
part of the structure. This duty being thus accurately ascertained, if a proper quantity and quality of material is
provided to fulfill the demand, and if proper care is taken to
secure excellence of manufacture, the result must be a safe
and durable bridge.




43
The St. Joseph bridge is from the designs of Mr. Willard S. Pope, the President and Engineer of the Detroit
Bridge and Iron Works, of Detroit, Michigan, the contractor for the entire work, both substructure and superstructure.  All of the iron was manufactured and fitted
at their extensive bridge works in Detroit. The care and
accuracy with which the work was done is evidenced by
the fact that when it catne to be put together in place, absolutely no fitting was required. The wide experience of
this well known company itn this class of work has brought
with it an accuracy of workmanship that is unsurpassed.
E R E C T I O N.
The work of erecting such a structure over the shifting,
turbulent sands of the Missouri river, was no inconsiderable problem.  The first span erected was the one reaching from  the Kansas shore eastwardly, between piers six
anld five. Next came the one between piers five and four.
These were both set up in the winter of 1872-73. N'eithler
of these spans was over the main channel of the river,
and the water was neither very deep nor very rapid. Piles
were driven into the sandy bed of -the river, which supported  the iron  work  while in process of being put together. During all this time the river was heavily frozen.
But before the next span could be reached and finished,
it was evident that the ice would probably go out, and in
going out, would surely take with it instantly whatever. of
temporary works or scaffolding might stand in its path.
Therefore no further attempt at raising was begun until
after the exit of the ice. About March 15, the ice moved
and active preparations were at once begun.  There now
remained to raise the draw-span and one three hundred




44
feet fixed span, both of them in mid channel.  The false
works for the draw were taken in hand first. Heavy piles
from fifty to sixty feet long were solidly driven, many of
them  to the bed-rock itself.  Thes were arranged in piers
about sixty feet apart, eight piles to each  pier, and
were well capped and braced.  They stood in from fifteen
to thirty-eight feet of water, in the midst of a fierce current.  Upon these piers were placed small spans of Howe
truss bridge, which formed the support for the iron-work,
travelers, etc., etc.  These works stood firmly as long as
they  were  wanted, and  the  process of  erecting  the
draw went so rapidly forward that the huge span was
swung into its position across the river in fifty days from
the tilme the first blow was struck.
On the 24th of March, the pile-driver was placed at
work at the staging for the last three hundred feet span,
between piers three and four.  The water was reasonably
low, and across a part of the space a sand-bar had fbrmed
reaching nearly to the surtace of the water.  Four piles
were driven in each bent, and the bents were spaced twenty
feet apart.  Heavy piles were used, and they were very
thoroughly driven.
This work was just fairly completed, when a sudden,
strong rise of the river swept the piles all out. Once more
the work was resumed.  Piles were driven heavier than
before, and thoroughly capped and braced, and once more
the river rose in its might and swept away the obstructions.
In these delays and losses, a month or more had passed.
It was now April 20. Bad weather almost constantly, the
river gradually rising to its June flood-the dangers daily
increasing rather than diminishing, and the hardest span
of all yet to raise, just in mid-channel, with high water




45
and islands of drifting snags. Two complete sets of false
works had been carried away like straws, and the strong
probability was that the third would be carried away likewise; and it might be, take a part or the whole of the iron
with it. But the work must be done.  Once nmore the
powerful pile-driver began operations.  This time a plan
was adopted similar to that used successfilly for the drawspan.  Piles were driven in piers about sixty feet apart.
They were from fifty to sixty-five feet long, and were very
thoroughly driven.  Short Howe trusses were placed upon
the piers.  Every energy was devoted to -this work.  On
the 2d of May, the first piece of iron was brought out
from the shore and put into place, and on the evening of
May 4 it was all together, and the span safe. The iron in
this span weighs two hundred and fifty tons. It was all
transported from the shore, a distance of about eight hundred feet, and hoisted into place and coupled up in about
thirty-six working hours. The sight of the turbulent water
surging and boiling around the piles below, like a fierce'
monster hungry for its prey, was eminently suggestive, and
every man worked with a will, and the result was that the
span was put in place quicker than any similar piece of
work was ever done before. Every one drew a long breath of
relief when it was finally pronounced safe. After this, the
work of completion was brief. The floor was rapidly laid,
and on May 20, the first train moved over the bridge.
CONTRACTOR.
The Detroit Bridge and Iron Works, of Detroit, Mich.,
was organized into a joint stock corporation in 1864.  Its
managers had, for some years previous, been engaged in
the construction of iron bridges for railroads, but as it was




46
deemed that its affairs could be better conducted as a corporation than as a private partnership, the change was
made accordingly.  Its works are in the Ninth Ward of
the City of Detroit, at the intersection of Twenty-second
street with the Michigan Central Railroad. Its shops, buildings and yard cover an area of about six acres of ground,
well provided with side tracks, etc.  About three hundred
mlen are ordinarily' employed in the shops.  It makes a
specialty of iron bridging and iron roofing.
One can hardly ride over any of the railroads of the
Northwest without crossing some of its bridges. The Michigan Central Railroad. the Chicago, Burlington & Quincy
Railroad, the Iliinois'Central Railroad, the Detroit & Milwaukee  [Railroad, the Chicago &  Northwestern Railway,
etc., etc., are stocked with bridges from  these works.  This
Company built the gre:lt bridges over the Mississippi river
at Burlington, Iowa; at Clinton, Iowa; at Quincy, Illinois,
and at Hannibal, Missouri.  These great works speak for
themselves.  For elegance of design, excellence of material
and workmanship, and for strengt}h and durability, they
are unsurpassed.
From  small beginnings, this Company has grown to a
commanding position.  Its constant policy has been to do
the best work, in the most honest and thorough manner.
and as a sample thereof, it can fairly refer to the St. Joseph Bridge.
Its officers are as follows:
WILLARD S. POPE, President and Engineer.
WILLIAM C. COLBURN, Secretary and Treasurer.
S. S. ROBINSON, Superintendent.
Mr. ROBINSON was at St. Joseph in charge of the Company's interests during the entire progress of the work. He




47
was assisted by Mr. J. L. PATTON, foreman of carpenters;
Mr. JAMES MANSON, foreman of stone-cutters and masons;
Mr. THOMAs  MALBON, foreman of machinery and caissonmen, and Mr. GEORGE STARKE, foreman of electing drawspan.
THE APPROACH ES.
The approaches of the bridge are easy, ornamental and
substantial, both being solid embankrnents of earth, properly
protected.
The west approach is 2316 feet long, and contains about
70,000 cubic yards of earth.  its eastern end extends out 180
feet fiom the west shore, around and envelopes tile west pier
of the bridge. Beginning at the pier the track is level for a
distance of 500 feet, after which, for a distance of' 1816 feet,
it descends on a grade of one foot in one hundred feet, or
about 52 feet to the mile, to a connection with the St. Joseph
and Denver City Railroad, on a straight line. There are two
wagon ways —one on either side.  For a distance of 100 feet
tromlin the end of the bridge, the approacil is floored and is
level. Thence the roadways descend on a grade of' five feet
in one hundred. They are mnacadamized, guttered and fenced.
The foundation or base of that part of' this approach reaching ifom the shore to and beyond the pier is a berme of alternate layers of brush and riprap, 20 feet wide, and, at the
head, sunken in 35 feet of water.  This extends from  the
shore on the north, eastward and around the pier, and back
to the shore again on the south. This enclosure was filled in
with sand, forming the emballkment for the approach. The
entire f'ace of the embankment, both above and below water, was
then covered with a slope wall, three feet thick at the base,
and one and a half feet at the top, the wall resting on the




48
berrne. It should be added that double rows of piles were
driven into the sandy bed of the river to hold the brush and
riprap of the berme while being built.
The east approach, starting from the east abutment, runs
81 feet straight and level; then 300 feet to the left on a six
degree curve, and with a descent of one foot in 400; thence on a
straight line. with the same grade, 233 feet, to a connection
with the various railroads, its total length being 714 feet.
The east abutment serves as a rest for the east end of the
80 feet span. It contains 48 cubic yards of masonry, and is
sirmounted by two handsome ornamental stone columns,
eight feet in height, bearing appropriate inscriptions.
COST OF THE BRIDCE.
Amount paid Detroit Bridge & Iron
Works for substructure and superstructure of the bridge proper,... $718,000
Approaches; including toll-houses, etc.,  $59,000
Dikes, etc., for river protection,.  55,000  117,000
All other expenses, including right-ofway, engineering, interest, discount and commissions on sale
of bonds, etc.,.....  174,000
$1,009,000
DIARY OF WORK ON THE BRIDCE.
Preliminary work commenced in June, 1871.
July 14tll.-Bridge permanently located.
July 28th-First car loads of stone arrived.
August 12th-Steanmer Huron arrived from St. Louis with
a tow of barges for contractor.




49
September 22d-Contractor set up pile driver.
September 23d-First piles for temporary track driven.
PIER VI.
October 5th, 1871 —Commenced framing caisson, and finished driving piles for its support.
October 10th-Cornmenced setting up boilers for pumping.
October 11th —Commenced setting up caisson for pier VI.
November 4th-Caisson completed.
November 6th-Cornmenced laying masonry.
Novemlber 9th-Commenced running sand pumps.
December 7th —Pier landed on bed-rock 45 feet below low
water.
This pier was comipleted Jatnu:ry 2d, 1872, and was composed of 116,000 teet of timber, 75 cubic yards of concrete,
and 629 cubic yards of masonry. It Is the west pier of the
bridge, near the Kansas shore.
PIER V.
November 23d, 1871-Commenced setting up caisson of
pier V.
December 27th-Caisson completed.
December 31st-Sand pumps at work.
January 4th, 1872 —First stone laid.
February 2d-Pier landed on bed-rock.
March 4th-Masonry finished.
This pier contains 142,000 feet of timber, 135 cubic yards
of concrete, and 933 cubic vyaids of masonry. Meanwhile
the temporary track had been extended to
PIER IV.
January 5th, 1872-Commenced setting up caisson of pier
IV.
February 12th-Blocking under caisson undermined by
7




50
current, and caisson dropped nine feet without sustaining any
injury.
February 17th —Caisson completed and commenced laying masonry.
March 13th  Pier landed on bed-rock.
Pier IV. contains 175,000 feet of timber, 134 cubic yards
of concrete, and 954 cubic yards of masonry.
UPPER DRAW REST.
By March 27th, 1872, the floating barges and trestles for
sustaining the caisson of the upper draw rest and pivot pier
were ready.
March 29th-Commenced setting up caisson for upper
draw rest.
April 23d-Towed it down the bayou.
April 27th-Moved it into position.
April 30th-Commenced lowering it.
May 4th-Pumps set to work.
May 6th —Commenced putting in rip-rap.
May 31st-Landed pier on bed-rock.
This structure, which acts as an ice breaker as well as a
rest for the draw span when opened, contains 380,000 feet of
timber, and 2,000 cubic yards of riprap, and weighs about
4,000 tons. It is faced with iron.
PIER II.
Pier II., or the pivot pier, was the next piece of work
undertaken. The caisson for this is 45x45 feet. Owing to the
extreme high water, it was not floated into position until late
in the season.
June 14th, 1872-Commenced setting up caisson.
July 16th-Finished caisson.
August 30th-Floated it down behind draw rest; lowered
it into the water and put on grillage.




51
September 12th —Dropped down to final position.
September 25th-Timber work completed.
September 26th-Masonry commenced.
November 6th-Landed on bed-rock.
This pier contains 345,000 feet of timber, 95 cubic yards
of riprap, and 1,913 cubic yards of masonry.  During its
progress, one of the pumping barges sprung a leak and capsized. Submarine divers subsequently recovered both barge
and mlachinery in good condition.
PIER III.
The caisson for pier III, was built in position, supported
by trusses resting on piles driven into the sandy bed of the
river in shallow water.
September 17th, 1872-Commenced setting up trusses.
Octoler 26th-Colrmeinced setting up caisson.
November 22d-Lowered caisson to sand.
December 2d-Timber work completed.
December 9th-Commenced laying stone.
January 16th, 1873-Landed pier on bed-rock.
This pier contains 199,000 feet of timber, 108 cubic yards
of riprap, and 1,142 cubic yards of masonry.
PIER I.
January 21, 1873-The caisson was launched.  While
letting the caisson slide, by means of ropes, into the river,
the ropers gave way, the caisson floating in the river.  It
was brought back all right and put in place, ready for sinking.
February 3-False bottom was taken and pumps started.
March 4-Landed on bed-rock.
March 5-Commenced concreting caisson.
March 14-Finished hoisting shaft and pipes, and the
pier taken charge of by the foreman of masons.




52
This pier contains 129,000 feet of timber, 83 cubic yards
of concrete and 773 yards of masonry.
SUPERSTRUCTURE.
November 7th, 1872-The first carload of iron shipped
from Detroit.
January 11th, 1873-The wall plates for the four corner
pedestals of;he west span set.
January 18th-The west span swung clear of its blocking.
January 20thl-Commenced raising the next span, between
piers four and five.
January 25th —Set the wall plates.
February 4th-The second fixed span swung clear.
March 10th-Conmmnenced on the turn-table of the drawspan.
April 6th-Driving piles for the false work of span between piers three and four.
April 15th —Commenced putting up the posts for the
draw-span; also the false work for the eighty-feet span.
April 28th —The draw-span closed for the first time.
May 2d-The raising of iron-work for the last span to
be completed was commenced.
May 5th-The last span was swung.
May 9th —The adju.stment of the last span completed,
and the work of putting on track and floor timbers begun.
May 12th-Commenced laying the rails for the last span.
May 20th —At 3 o'clock P. M. an engine with the officers
and invited visitors of the Bridge Company, rode safely
over the bridge, and from  that time trains have crossed
and re-crossed regularly.
May 27-The bridge. was formally tested by an engine




and a heavily loaded freight train, equivalent to a load ot
about one ton per lineal foot of track.  Under the action
of this load, the spans three hundred feet long deflected at
the centre two and nine-sixteenths inches; the eighty-foot
span deflected three-quarters of an inch; and each wing ot
the draw-span deflected five-eighths of an inch. The structures in each case recovered themselves perfectly after the
removal of the load.
May 31st-The City of St. Joseph formally opened the
bridge and dedicated it to public uses by a grand celebration, wherein all the citizens participated, together with a
large number of invited guests, and a great concourse ot
people from the surrounding country. Universal good feeling
prevailed, and each one congratulated himself and his friends
that the great work had finally been brought to a happy issue.