» CO* ■* >o" o' t-" x" oT
DISCUSSION ON STABILITY OF BENCH MARKS.
TABLE No. 2.
Hickory . .
Linden . . .
J. James R. Croes, M. Am. See. C. E.— I think that Mr. Odell has
some data in regard to differences of elevation in the same bench mark
in the vicinity of New York.
r. S. Odell, M. Am. Soc. C. E. — I have noted some changes in
bench marks, but am not able to give the exact differences; I think it
"was due to some settlement of the foundations of the bench mark.
They were taken on the basin covers of the receiving basin in 129th
Street, in the vicinity of Second and Third Avenues. There seemed to
be about i of an inch difference, as near as I can remember, in relation
to other prominent objects in the same vicinity.
Mr. Croes. — Was there not an instance where a point which was sup-
posed to be pretty permanent was found to vary every few days?
Mr. Odell. — Well, not every few days, but every few months. I
think you probably refer to the bench marks on the stairway foundations,
but we hardly considered those to have been of such a construction
that they would not vary somewhat; we found they did vary, but we
thought it was due to the nature of the foundation.
By reference to the notes I find that the basin cover at 129th Street
and Second Avenue settled 0.130 of 1 foot in eighteen months, while that
at 129th Street and Third Avenue had become 0.060 of 1 foot higher
during the same period, and the stairway foundation had settled 0.2iO
of 1 foot.
76 DISCUSSION ON" STABILITY OF BENCH MARKS.
Mr. A. Ftelet, M. Am. Soc. C. E., stated that in connection with
water gaugings which required accurate levels to be taken of the surface
of water running in a long flume, and the surrounding grounds being
very swampy and unreliable for the establishment of ordinary benches,
he used to advantage some long iron rods driven through many feet of
swampy mud into the solid bottom. The top of the rod furnished per-
manent and very accurate benches.
H. W. Brinckerhofp, M. Am. Soc. C. E. — Some eighteen years ago
or more Mr. John F. Ward, M. Am. Soc. C. E., then chief engineer of
the Jersey City Water Works, and whose assistant I then was, put a
couple of standard benches in the Jersey City parks, each of which con-
sisted of a 2 J -inch iron rod perhaps 8 feet in length; the upper end
stood just out of the ground and was slightly convex, while the lower
end had cast around it a disk of cast-iron about 2 feet in diameter.
Of course they had to have a hole dug to set them ; but after they had
been set they could be depended on for all time, I presume, as they were
anchored below the reach of frost or other probable disturbance. They
gave very satisfactory results as long as I had occasion to use them, and
I understand they are still unmoved and in good condition.
"^ P. F. Brendlinger, M. Am. Soc, C. E. — I was very much interested
in the paper this evening; the fluctuations from year to year are certainly
very interesting and curious. It strikes me, however, that Mr. Cooley
should have had more than one permanent gas pipe bench to compare
with, or better still, have this one gas i^ipe bench and one of some other
material somewhat deejDer in the ground, then compared these benches
with those on trees. This fluctuation reminds me very much of a case
we had in Pittsburgh in 1875. There was a high water mark established
on a brewery. This was a flood mark; the highest flood ever recorded in
Pittsburgh, that of 1832. In 1875 I had occasion to build a bridge in
that vicinity, the Point Bridge. We had to raise the street at the
brewery. Some engineers took elevations on that high water mark; it
was about 31 feet above low water level; one year, 1877, they found it
was 35 i feet; it had risen a foot and a half in two years. They could
never understand how that was until I explained that I had raised the
building 18 inches and the high water mark went uji with it and was
Mr. Croes. — Had they been working from that bench in the mean-
Mr. BRENDiiiNGER.— They tested it; they said it had risen rapidly in
the two years.
DISCUSSION OX STABILITY OF BENCH 3IAKKS.
Geokge W. C001.EY, M. Am. Soc. C. E.-I tliink there can be no
ques ion as to the stability of my standard bench. Two reference
benches were established at the same time-one of the same description
and size, and another of gas pipe driven into the bottom of the lake
belo^^ the reach of ice or other disturbing cause. The latter was used
to regulate a water gauge and the gauge frequently tested by the
standard bench. Tests made during the first three yea/s of the expert
tTer!' tZ^i""" '^'"°^ ^^ *^' '*'^^"^^^' "^^^ ^' ^^^"^^ impossible that
there should be any, as the pipe was not in contact with the earth at any
point except 7 feet below the surface, and was well protected. Another
circumstance in connection with these experiments not mentioned fn
my paper was the fact that nails driven into some of the trees about four
fyt above ground maintained for five years the same relative position
Mith regard to the nails on the benches. Onlv three of these were
tested, the others being covered with a growth of bark
AMERICAN SOCIETY OF CIVIL ENGINEERS.
I INSTITUTED 1852.
NoTB. — This Society is not responsible, as a body, for the facts and opinions advanced in
any of its publications.
(Vol. XX. -February, 1880.
DESCRIPTION OF GUARD GATES AT THE POINT
STREET BRIDGE AT PROVIDENCE, R. I.
By WiiiiiiAM D. Bullock, M. Am. Soc. C. E.
The Point Street Bridge spans the Providence Paver, and is located
about one-half mile below the head of navigation.
It consists of three spans. Each of the two fixed spans has a clear
sj^an of about 143 feet, and the draw span, located between the latter, is
250 feet long, over all, with two clear openings for the passage of ves-
sels, of 100 feet each. The fixed spans are of the Mosely Arch pattern,
and -were built by the Mosely Iron Company of Boston about 1869-70.
The draw span was built by Charles Macdonald, M. Am. Soc. C. E., to-
replace the original one built by the Mosely Iron Company, which-
proved unsatisfactory. It is supported on a Seller's table, and is operated
by steam power, the engine being located at the draw center, as shown
on the general plan, Plate III.
This bridge is a through bridge, with one driveway 2-4^ feet wide be-
tween wheel guards, aud two sidewalks each about 6 feet wide, the total,
■width out to out being 40 feet.
BULLOCK ON BRIDGE GUARD GATES.
The bridge was opened to travel October 22d, 1872, and no guard
gates were placed upon it until some time in the fall of 1874 when one
gate was placed at each end of the bridge, closing only the right hand
half of the driveway. These gates, which were erected at a cost of
U 000, consisted of a single bar, similar to those in use at railroad cross-
ings, and were operated from the draw center. They were in use until
1875, when they were removed, having proved unsatisfactory as safe-
guards, and giving much trouble in operation.
From that time until the erection of the present gates, the bridge
has been without guard gates or protection of any kind when the draw
Tlie number of teams passing over this bridge daily from 6 30 a m
to 6.30 P.M. varies from about 1 200 to 1 500, and the number of pedes- -
trians passing within the same hours is about 3 000.
The average number of daily openings of the draw for the years
1885-88 was 38 ; and the greatest number of openings for the twenty-
four hours of any one day during the same years was 79. The average
time that the bridge was closed to travel, for each opening of the draw
for^the above-named years, was 4.52, 4.58, 4.29 and 3.72 minutes respect-
No trotting over the bridge is allowed, and all teams are required to
Keep to the right.
March 20th, 1883. a resolution of the City Council was approved
directing the Committee on Bridges to erect guard gates at the Point
The problems presented for solution in designing gates for this loca-
tion were difficult ones. The gates must be safe; must close the
approaches to the draw to both pedestrians and teams ; must be operated
and controlled at the draw center ; must not interfere with the operation
of the draw nor call for additional help ; must cause but little if
any. delay to travel over the bridge, or to navigation through the
Under these conditions the writer was called upon to make designs
for the gates. Careful inquiry failed to show any precedent in the con-
struction of gates under such conditions.
An exhaustive study of the subject was made, and sketch plans pre-
pared in which the application of water, compressed air, and electricity
as motors was considered. These, although more easily operated ani
80 BULLOCK OX BRIDGE GUARD GATES.
controlled from the draw center than steam, were attended with special
difficulties, and would probably be more expensive in maintenance.
Steam jjowerwas not at first regarded with favor, owing to the apparent
difficulty in designing suitable connections between the draw and shore
spans. Finally the solution of the problem seemed to depend upon the
discovery of some device by means of which the power, located at the
draw center, could be transmitted to the gates on the fixed spans. After
much study the tongue and grooved slide attachment, as shown on the
accompanying i:)lans, was devised, by means of which a simple, positive
and automatic connection between the draw and fixed span was secured,
which has i:)roved entirely satisfactory.
With suitable connections thus assured, the steam power used in
operating the draw became the most available power for operating the
The following description, with Plates III, IT, V, YI, will exjilain
the construction of the gates and machinery, and the manner of operat-
By reference to the general jjlan, it will be seen that the gates are
located on the fixed spans about 16 feet from thi^ ends of the draw, thus
leaving a space on the fixed span where pedestrians may wait when
stopjied by the gates; and also permitting the gates to be closed as soon
as possible after the teams leave the draw.
The gates swing on vertical posts, and the frames are constructed of
channel iron, with diagonal tie rods with turn-buckle adjustments.
To the frames are bolted Ix'iJ inches yellow pine pickets, of such
length as to give a height for the gates of about 5 feet 3 inches above the
floor. The posts are of solid wrought iron 2i inches square for the drive-
way gates, lil^ inches square for the sidewalk gates, and If inches square for
the safety gates. These posts extend through and beneath the flooring,
and to this extension of each driveway gate post is attached a 2J:-inch
spur gear, which meshes into a like gear on the sidewalk gate i)ost. To
the driveway gate post just below the 21-inch gear is also attached a
36-inch grooved pulley, around which jjasses the wire rope by which the
power is applied.
The driveway is closed by two gates swinging from the truss towards
the center, and both latching to the same wooden post in the center of
the driveway. Each sidewalk is closed by two gates, the larger one
swinging from the truss towards the outside of the sidewalk. Opposite
BULLOCK ON BRIDGE GUARD GATES. 81
to the latter, upon an extension of the sidewalk, is placed a small safety
gate, so arranged that it is free to swing until the end of the sidewalk
gate swings nearly opposite to it, and the space (3 or 4 inches) between
the ends of the two, is too small to permit a person to get caught be-
tween them, when a latch beneath the flooring is thrown by an arm on
the sidewalk gate gear, and the safety gate is securely fastened.
The driveway and sidewalk gates swing away from the draw when
closing, and towards the draw and away from the waiting public when
At the upper end of each driveway gate post is placed an alarm bell»
which is rung at short intervals by the movement of the gate when
swinging in either direction. The weight of each driveway and side-
walk gate is sui^ported by a steel collar shrunk on the post, and turning
on a bronze ring, held firmly in place by a cast-iron shoe bolted to the
flooring. All of the gates are painted white, which contrasts with the
olive color of the bridge, and thus makes them more conspicuous as
barricades in case of runaways.
The gates are closed by steam jjower and are opened by counter
Supported upon the turn-table of the draw beneath the flooring
is a horizontal shaft ci.rrying two grooved drums, and connected
with the engine by gearing and friction clutches, which are operated by
hand levers on the deck of the bridge.
Two wire roj^es wind upon each drum from opposite directions; one
entering on the lower side, and connecting with the gates which close
one-half of the driveway and one sidewalk at one end of the draw; and
the other entering upon the upper side of the same drum, and connect-
ing with the corresponding gates at the diagonally opposite corner.
The two drums although on the same shaft are entirely independent
of each other, and are set in motion by cone frictions operated by sejja-
rate hand levers on the deck of the bridge.
The power is transmitted from the drums to the gates by |-inch iron
rods and J-inch wire ropes carried on guide pulleys beneath the flooring.
The connections between the draw and fixed spans are automatic, so
that when the gates have been closed all connections with the shore spans
are released as the draw moves off.
82 BULLOCK OX BRIDGE GUARD GATES.
The draw can be turned in either direction, or reversed, end for end,
without interfering with the connections, and as the draw returns to
place, the connections are again established.
At each of the four corners of the draw and in line with the railing
is placed a frame, constructed of angle and tee iron, and supporting two
1^-inch vertical steel rods, upon which works a tongue slide. Upon the
fixed spans and directly opposite, are similar frames each having two
vertical rods, upon which works a grooved slide, which engages with the
tongue slide on the draw. Neither the tongue nor the grooved slide
can be moved vertically without carrying the other with it; but the two
are entirely independent of each other when moved horizontally. The
tongue slides are connected by rods and wire ropes with the drums at
the center, and the grooved slides are connected with the grooved
l^ulleys on the gate posts by wire ropes. On the ends of the top and
bottom rail of each driveway gate is a projecting latch, which, as the
end of the gate comes near^to the wooden jsost at the center, engages
with counterbalanced catches, thus fastening the gate securely. The
sidewalk gates are held in position by the gear connection with the
driveway gates. The gates are all unlatched at the same time by an
independent lever at the center of the draw; the connection between the
draw and fixed spans being made by a rod on the draw pushing against
a plate on the fixed sisan.
The gates are operated as follows :
When the signal to open the draw is heard, the engine is started and
the hand lever of the main friction clutch which connects the engine
with the gate machinery is thrown over. The signal — three strokes of
the bell — is given by the superintendent for all passing over the bridge
The No. 1 lever is thrown over, and the drum set in motion,,
which closes the pair of gates at the diagonally opposite corners, on the
sides of the bridge by which teams approach the draw. The wire ropes
wind on the drum thus set in motion, from opposite directions, raising
the tongue slides and carrying with them the grooved slides on the fixed
spans. Motion is thus communicated by the grooved slides to the wire
ropes which pass around the pulleys on the driveway gate posts, and the
gates are turned through an angle of 90 degrees and latched to the cen-
ter posts. Just as the gates latch, the hand lever at the center is
thrown back, which disconnects the drum from the engine. The ex-
BULLOCK ON" BRIDGE GUARD GATES. 83
treine backward throw of the lever oj^erates a brake on the drum, which
holds it firmly, and keeps the tongue slide exactly in the position where
it stops. After the teams have all left the draw, the second pair of gates
is closed in the same manner by the No. 2 lever. The main friction
clutch lever is then thrown back and the draw is ready to be opened.
It will be observed that the only delay to the public from operating
the gates, is the time which it takes to close the second pair of gates,
which does not exceed about eight seconds. In opening the gates there
is practically no delay to the i^ublic in waiting. As soon as the draw
comes to rest the gates are all unlatched together and opened by the
counter weights, the movement of the gates being under control of the
superintendent at the center by means of the brakes on the drums. The
counter weights are adjustable, varying from about 100 pounds in still
weather, to 125 pounds or more in windy weather, for each of the four
In the erection of the gates and operating machinery, the work was
so conducted, that, although requiring considerably more time, the
bridge was not closed to travel.
The general arrangement of the gates, and the method of operating,
especially the automatic connection between the draw and fixed spans,
are believed to be entirely new in design.
The gates were erected in the fall of 1884 and were put into regular
operation January 17th, 1885, and have since been in constant use
up to the present time, a period of more than four years, giving entire
satisfaction to the traveling public, and fulfilUng all the requirements
of safety, convenience and economy.
During the period of four years in which the gates have been in
operation no repairs of importance have been made, except to renew the
•jvire ropes as they have worn out; and no change in the machinery has
been made, except to substitute for the two grooved drums at the center
new ones with deeper grooves to prevent the wire ropes from getting out
of place, and stranding on the edges of the grooves. The new drums
were also lagged with hard wood on the surface against which the brake
pressed, to avoid the slipping of the brakes when the frost was coming
out of the iron, which had given some trouble under certain conditions
of the weather in the winter.
This change in the drums has entirely remedied the trouble from the
two sources mentioned above.
84 BULLOCK ON BRIDGE GUARD GATES.
The gates and operating machinery were designed, and their erection
superintended by the writer, acting under the general instruction of the
City Engineer, Samuel M. Gray, M. Am. Soc. C. E. Valuable assistance
was rendered by H. N. Francis, M. Am. Soc. C. E., in the preparation
of working drawings and the erection of the gates.
POINT ST. BRIDGE GATES.
PLAN AND ELEVATION
SHOWING GENERAL ARRANGEMENT AND CONNECTIONS OF GATES.
PROVIDENCE R.I. 1884,
GROOVE SLIDE AND FRAME.
SIDE ELEVATION OF AUTOMATIC CONNECTION
BETWEEN THE DRAW AND SHORE SPANS.
TONGUE SLIDE AND FRAME.'
POINT ST. BRIDGE GATES
PLAN AND ELEVATION.
WITH DETAILS OF AUTOMATIC CONNECTIONS.
PROVIDENCE R. I. 1884.
St»L£ Of FEtT FOR PLAN MO ELtVATlON.
VOL XX . N? 405
RIDGE GUARD GATES.
POINT ST. BRIDGE GATES.
SIQEW4LK OArC SHOE.
DRIVEWAY GATE SHOE.
AMERICAN SOOIET? OF CIVIL ENGINEERS.
Note.— This Society is not responsible, as a body, for the facts and opinions advanced in
any of its publications.
(Vol. XX.— March, 1889.)
THE IMPROVEMENT OF THE MISSISSIPPI RIVER.*
By William Starling, M. Am. Soe. C. E.
The Mississippi is above all things a silt-bearing stream, flowing
through a bed of its own creation. It is never clear, even at its lowest;
and at its floods it is charged with sediment to an enormous extent.
This involves the following consequences: The banks are low and sub-
ject to overflow by all floods greater than the mean. Banks and bottom
are friable, and, therefore, liable to degradation and erosion. The chan-
nel is shifting and unstable, and subject to obstruction by shoals.
The Mississippi, like all other streams, is comi30sed of tortuous
bends, which modify, in the most striking manner, the laws of its flow.
In the portion of its course which we are considering it runs through
a bed of comparatively recent origin. It is seldom that it encounters a
portion of any formation older than that which constitutes its present
flood-plain. At a few points the banks consist of bluffs of a quaternary
formation, called by geologists loess, from a similar formation on the
Rhine; at a few more, its bed trenches on another quaternary formation,
called the " Port Hudson " clay, not very dissimilar to that of the present
alluvium, and deposited by the river itself in its ancient state, at an
epoch anterior to that of the i^resent stream. It has been a much
mooted question how great a part of the present bed is occupied by this
*This paper was prepared for the University of the City of New York. It is now pub-
lished for the first time through the courtesy of the Faculty of that Institution.
STARLING OX THE MISSISSIPPI RIVER.
older and harder clay; but the investigations of the Mississii)pi Elver
Commission apj^ear to point to the conclusion that the proportion is
The alluvium composing the banks and the bed is extremely variable
in composition, being sometimes nearly pure sand, sometimes nearly
pure clay, sometimes made u^) of both ingredients in all proportions.
These different qualities of soil are disposed in strata of every variety
Thus the banks are friable, but in very dififerent degrees. Usually,
however, even the toughest clay is underlaid by strata of lighter ma-
terial, which, as will soon be seen, diminishes the resistiug power of
the stronger earth.
The theory of the completed flood-plain of a river is well known.
The sediment brought from the torrential and fluvial parts is deposited
on the bottom, and by overflow on the banks of the stream in its alluvial
part; thus raising the upper portion of the flood-plain, and steepening its
slope until the velocity of the water becomes suflficient to carry the load
without diminution to the sea. Xot every flood-plain is completed.
Some are yet in a state of transition and have not attained stability.
Bends introduce a disturbing element into this process. The cur-
rent, flowing with the normal, or even with a slightly accelerated
velocity, encounters the resistance of the bank, say at A (see Fig. 1),
placed at a somewhat abrupt angle to the course of the stream.
STARLING OX THE MISSISSIPPI RIVEE. 87
A portion of its energy is directed against the soft material composing
the bank, jiromptly dislodges it and carries it a certain distance.
It is supposed that the normal velocity is sufficient, and no more, to
carry to the sea the sediment brought to the alluvial portion from
above. This will not prevent it from acting on the banks. Be the
■water never so highly charged, provided its fluidity be not materially
impaired, when it encounters the bank at an abrupt angle, it will not
fail to dislodge a portion of the material. This action is purely me-
chanical. It is the eftect of direct impact, like the blow of a pickaxe cr
a hydraulic jet. The earthy matter thus committed to the water will not
sink directly to the bottom. It will be carried a hundred or a thousand
feet, or a mile, or ten miles, and eventually dropped, and this although
there were no slackening of the velocity. By hypothesis the water was
already loaded with all it could permanently transport, when it acquired
this additional load, which must therefore be only temporary, a forti-
ori then must be deposited when the velocity is diminished. The