ENGINEERING AND TRANSPORTATION.
The field of service of a civil engineer has thus been eloquently stated
by a recent writer in _Chambers’s Journal_:
“His duties call upon him to devise the means for surmounting obstacles
of the most formidable kind. He has to work in the water, over the
water, and under the water; to cause streams to flow; to check them from
overflowing; to raise water to a great height; to build docks and walls
that will bear the dashing of waves; to convert dry land into harbours,
and low water shores into dry land; to construct lighthouses on lonely
rocks; to build lofty aqueducts for the conveyance of water, and
viaducts, for the conveyance of railway trains; to burrow into the
bowels of the earth with tunnels, shafts, pits and mines; to span
torrents and ravines with bridges; to construct chimneys that rival the
loftiest spires and pyramids in height; to climb mountains with roads
and railways; to sink wells to vast depths in search of water. By
untiring patience, skill, energy and invention, he produces in these
several ways works which certainly rank among the marvels of human
power.”
The pyramids of Egypt, the roads, bridges and aqueducts built by the
Chinese and by Rome; the great bridges of the Middle Ages, and
especially those built by that strange fraternal order known as the
“Brothers of the Bridge”; the ocean-defying lighthouses of a later
period--these, and more than these, attest the fact that there were
great engineers before the nineteenth century.
But the engineering of to-day is the hand-maid of all the Sciences; and
as they each have advanced during the century beyond all that was
imagined, or dreamed of as possible in former times, so have the labours
of engineering correspondingly multiplied. No longer are such labours
classified and grouped in one field, called Civil Engineering, but they
have been necessarily divided into great additional new and independent
fields, known as Steam Engineering, Mining Engineering, Hydraulic
Engineering, Electrical Engineering and Marine Engineering. Within each
of these fields are assembled innumerable appliances which are the
offspring of the inventive genius of the century just closed.
We have seen how one discovery, or the development of a certain art,
brings in its train and often necessitates other inventions and
discoveries. The development and dedication of the steam engine to the
transportation of goods and men called for improvements in the roads and
rails on which the engine and its load were to travel, and this demand
brought forth those modern railway bridges which are the finest examples
in the art of bridge making that the world has ever seen.
The greatest bridges of former ages were built of stone and solid
masonry. Now iron and steel have been substituted, and these light but
substantial frameworks span wide rivers and deep ravines with almost the
same speed and gracefulness that the spider spins his silken web from
limb to limb. These, too, waited for their construction on that next
turn in the wheel of evolution, which brought better processes in the
making of iron and steel, and better tools and appliances for working
metals, and in handling vast and heavy bodies.
The first arched iron bridge was over the Severn at Coalbrookdale,
England, erected by Abraham Darby in 1777. In 1793 one was erected by
Telford at Buildwas, and in the same year Burden completed an arch
across the weir at Sunderland. The most prominent classes of bridges in
which the highest inventive and constructive genius of the engineers of
the century are illustrated are known as the _suspension_, the _tubular_
and the _tubular arch_, the _truss and cantilever_.
Suspension bridges consisting of twisted vines, of iron chains, or of
bamboo, or cane, or of ropes, have been known in different parts of the
world from time immemorial, but they bear only a primitive and
suggestive resemblance to the great iron cable bridges of the nineteenth
century. The first notable structure of this kind was constructed by Sir
Samuel Brown, across the Tweed at Berwick, England, in 1819. Brown was
born in London in 1776 and died in 1852. He entered the navy at the age
of 18, was made commander in 1811, and retired as captain in 1842. We
have alluded to the spider’s web, and Smiles, in his _Self Help_,
relates as an example of intelligent observation that while Capt Brown
was occupied in studying the character of bridges with the view of
constructing one of a cheap description to be thrown across the Tweed,
near which he lived, he was walking in his garden one dewy autumn
morning when he saw a tiny spider’s web suspended across his path. The
idea immediately occurred to him of a bridge of iron wires. In 1829
Brown also was the engineer for suspension bridges built over the Esk at
Montrose and over the Thames at Hammersmith. Before that time, a span in
a bridge of 100 feet was considered remarkably long. Suspension bridges
are best adapted for long spans, and have been constructed with spans
more than twice as long as any other form. Sir Samuel Brown’s bridge had
a span of 449 feet. This class of bridges is usually constructed with
chains or cables passing over towers, with the roadway suspended
beneath. The ends of the chains or cables are securely anchored. The
cables are then passed over towers, on which they are supported in
movable saddles, so that the towers are not overthrown by the strain on
the cables. Nice calculations have to be made as to the tension to be
placed on the cables, the allowance for deflection, and the equal
distribution of weight. The floor-way in the earlier bridges of this
type was supported by means of a series of equidistant vertical rods,
and was lacking stiffness, but this was remedied by trussing the road
bed, using inclined stays extending from the towers and partially
supporting the roadway for some distance out from the tower.
The next finest suspension bridge was constructed by Thomas Telford and
finished in 1826, across the Menai Strait to connect the island of
Anglesea with the mainland of Wales. Telford was born in Dumfriesshire,
Scotland, in 1757, and died in Westminster in 1834. Beginning life as a
stone mason, he rose by his own industry to be a master among architects
and a prince among builders of iron bridges, aqueducts, canals, tunnels,
harbours and docks.
The Menai bridge was composed of chains or wire ropes, each nearly a
third of a mile in length, and which descended 60 feet into sloping pits
or drifts, where they were screwed to cast-iron frames embedded in the
rocks. The span of the suspended central arch was 560 feet, and the
platform was 100 feet above high water. Seven stone arches of 52½
feet span make up the rest of the bridge.
But a suspension bridge was completed in 1834 by M. Challey of Lyon over
the Saane at Fribourg, Switzerland, which greatly surpassed the Menai
bridge. The span is 880 feet from pier to pier, and the roadway is 167
feet above the river. It is supported by four iron wire cables, each
consisting of 1056 wires. It was tested by placing 15 pieces of
artillery, drawn by 50 horses and accompanied by 300 men crowded
together as closely as possible, first at the centre, and then at each
extreme, causing a depression of 39½ inches, but no sensible
oscillation was experienced.
Isambard K. Brunel was another great engineer, who constructed a
suspension bridge at the Isle of Bourbon in 1823, and the Charing Cross
over the Thames at Hungerford in 1845, which was a footbridge, having a
span of 675 feet, the longest span of any bridge in England. Then
followed finer and larger suspension bridges in other parts of the
world. It was across the Niagara in front of the great falls that in
1855 British America and the United States were joined by a magnificent
suspension bridge, one of the finest in the world, and the two English
speaking countries were then physically and commercially united. At the
opening of the bridge, one portion of which was for a railway, the
shriek of the locomotive and the roar of the train mingled with the roar
of the wild torrent 250 feet below. The bridge, 800 feet long, is a
single span, supported by four enormous cables of wire stretching from
the Canadian cliff to the opposite United States cliff. The cables pass
over the tops of lofty stone towers arising from these cliffs, and each
cable consists of no less than 4,000 distinct wires. The roadway hangs
from these cables, suspended by 624 vertical rods.
The engineer of this bridge was John A. Roebling, a native of Prussia,
born there in 1806, and who died in New York in 1869. He was educated at
the Polytechnic School in Berlin, and emigrated to America at the age of
25. His labors were first as a canal and railway engineer, then he
became the inventor and manufacturer of a new form of wire rope, and
then turned his attention to the construction of aqueducts and
suspension bridges. After the Niagara bridge, above described, he
commenced another bridge of greater dimensions over the same river,
which was finished within two or three years. His next work was the
splendid suspension bridge at Cincinnati, Ohio, which has a clear span
of 1057 feet. In 1869, in connection with his son, Washington A.
Roebling, he commenced that magnificent suspension bridge to unite the
great cities of New York and Brooklyn, and which, by its completion,
resulted in the consolidation of those cities as Greater New York. The
Roeblings, father and son, were to the engineering of America what
George Stephenson and his son Robert were to the locomotive and railway
and bridge engineering of Great Britain.
The Brooklyn bridge, known also as the East River bridge, was formally
opened to the public on the 24th of May 1883. Most enormous and
unexpected technical difficulties were met and overcome in its
construction. Its total length is nearly 6,000 feet. The length of the
suspended structure from anchorage to anchorage is 3,454 feet. A
statement of the general features of this bridge indicates the nature of
the construction of such bridges as a class, and distinguishes them from
the comparatively simple forms of past ages. This structure is supported
by two enormous towers, having a height of 276 feet above the surface of
the water, carrying at their tops the saddles which support the cables,
and having a span between them of 1,595 feet. The towers are each
pierced by two archways, 31½ feet wide, and 120½ feet high,
through which openings passes the floor of the bridge at the height of
118 feet above high water mark. There are four supporting cables, each
16 inches in diameter, and each composed of about 5,000 single wires.
The wire is one-eighth size; 278 single wires are grouped into a rope,
and 19 ropes bunched to form a cable. The iron saddles at the top of the
lofty towers, and on which the cables rest, are made movable to permit
its expansion and compression--and they glide through minute distances
on iron rollers in saddle plates embedded and anchored in the towers, in
response to strains and changes of temperature. The enormous cables pass
from the towers shoreward to their anchorages 930 feet away, and which
are solid masses of masonry, each 132 x 119 feet at base and top, 89
feet high, and weighing 60,000 tons. The bridge is divided into five
avenues: one central one for foot passengers, two outer ones for
vehicles, and the others for the street cars. The cost of the bridge was
nearly $15,000,000.
Twenty fatal and many disabling accidents occurred during the
construction of the bridge. The great engineer Roebling was the first
victim to an accident. He had his foot crushed while laying the
foundation of one of the stone piers, and died of lockjaw.
It was necessary to build up the great piers by the aid of caissons,
which are water-tight casings built of timber and metal and sunk to the
river bed and sometimes far below it, within which are built the
foundations of piers or towers, and into which air is pumped for the
workmen. A fire in one of the caissons, which necessitated its flooding
by water, and to which the son, Washington Roebling, was exposed,
resulted in prostrating him with a peculiar form of caisson disease,
which destroyed the nerves of motion without impairing his intellectual
faculties. But, although disabled from active work, Mr. Roebling
continued to superintend the vast project through the constant mediation
of his wife.
_Tubular Bridges._--These are bridges formed by a great tube or hollow
beam through the center of which a roadway or railway passes. The name
would indicate that the bridge was cylindrical in form, and this was the
first idea. But it was concluded after experiment that a rectangular
form was the best, as it is more rigid than either a cylindrical or
elliptical tube. The adoption of this form was due to Fairbairn, the
celebrated English inventor and engineer of iron structures. The Menai
tubular railway bridge, adjacent to the suspension bridge of Telford
across the same strait, and already described, was the first example of
this type of bridge. Robert Stephenson was the engineer of this great
structure, aided by the suggestions of Fairbairn and other eminent
engineers. This bridge was opened for railway traffic in March, 1850. It
was built on three towers and shore abutments. The width of the strait
is divided by these towers into four spans--two of 460 feet each, and
two of 230 feet. In appearance, the bridge looked like one huge, long,
narrow iron box, but it consisted really of four bridges, each made of a
pair of rectangular tubes, and through one set of tubes the trains
passed in going in one direction, and through the other set in going the
opposite direction. These ponderous tubes were composed of wrought-iron
plates, from three-eighths to three-fourths of an inch thick, the
largest 12 feet in length, riveted together and stiffened by angle
irons. They varied in height--the central ones being the highest and
those nearest the shore the lowest. The central ones are 30 feet high,
and the inner ones about 22 feet. Their width was about 14 feet. They
were built upon platforms on the Caernarvon shore, and the great problem
was how to lift them and put them in place, especially the central ones,
which were 460 feet in length. Each tube weighed 1,800 pounds, and they
were to be raised 192 feet. This operation has been described as “the
grandest lift ever effected in engineering.” It was accomplished by
means of powerful hydraulic presses. Another and still grander example
of this style of bridge is the Victoria at Montreal, Canada. This also
was designed by Robert Stephenson and built under his direction by James
Hodges of Montreal. Work was commenced in 1854 and it was completed in
December, 1859, and opened for travel in 1860. It consists of 24 piers,
242 feet apart, except the centre one, from which the span is 330 feet.
The tube is in sections and quadrangular in form. Every plate and piece
of iron was made and punched in England and brought across the Atlantic.
In Canada little remained to be done but to put the parts together and
in position. This, however, was in itself a Herculean task. The enormous
structure was to be placed sixty feet above the swift current of the
broad St. Lawrence, and wherein huge masses of ice, each block from
three to five feet in thickness, accumulated every winter. The work was
accomplished by the erection of a vast rigid stage of timber, on which
the tubes were built up plate by plate. When all was completed the great
staging was removed, and the mighty tube rested alone and secure upon
its massive wedge-faced piers rising from the bedrock of the flood
below.
_The Tubular Arch Bridge._--This differs from the tubular bridge proper,
in that the former consists of a bridge the body of which is supported
by a tubular archway of iron and steel, whereas in the latter the body
of the bridge itself is a tube. The tubular arch is also properly
classed as a girder bridge because the great tube which covers the span
is simply an immense beam or girder, which supports the superstructure
on which the floor of the bridge is laid. A fine illustration of this
style of bridge is seen in what is known as the aqueduct bridge over
Rock Creek at Washington, D. C., in which the arch consists of two
cast-iron jointed pipes, supporting a double carriage and a double
street car way, and through which pipes all the water for the supply of
the City of Washington passes. General M. C. Meigs was the engineer.
Another far grander illustration of such a structure, in combination
with the truss system, is that of the Illinois and St. Louis bridge,
across the Mississippi, of which Captain James B. Eads was the engineer.
There are three great spans, the central one of which has a length of
about 520 feet, and the others a few feet less. Four arches form each
span, each arch consisting of an upper and lower curved member or rib,
extending from pier to pier, and each member composed of two parallel
steel tubes.
_Truss and truss arched bridges._--These, for the most part, are those
quite modern forms of iron or wooden bridges in which a supplementary
frame work, consisting of iron rods placed obliquely, vertically or
diagonally, and cemented together, and with the main horizontal beams
either above or below the same, to produce a stiff and rigid structure,
calculated to resist strain from all directions.
Previous to the 19th century, the greatest bridges being constructed
mostly of solid masonry piers and arches, no demand for a bridge of this
kind existed; but after the use of wrought iron and steel became
extensive in bridge making, and as these apparently light and airy
frames may be extended, piece by piece across the widest rivers,
straits, and arms of the sea, a substitute for the great, expensive, and
frequent supporting piers became a want, and was supplied by the system
of trusses and truss arches. The truss system has also been applied to
the construction of vast modern bridges in places where timber is
accessible and cheap. Each different system invented bears the name of
its inventor. Thus, we have the Rider, the Fink, the Bollman, the
Whipple, the Howe, the Jones, the Linville, the McCallum, Towne’s
lattice and other systems.
What is called the cantilever system has of late years to a great extent
superseded the suspension construction. This consists of beams or
girders extending out from the opposite piers at an upward diagonal
angle, and meeting at the centre over the span, and there solidly
connected together, or to horizontal girders, in such manner that the
compression load is thrown on to the supporting piers, upward strains
received at the centre, and side deflections provided against. It is
supposed that greater rigidity is obtained by this means than by the
suspension, and, like the suspension, great widths may be spanned
without an under supporting frame work. Two fine examples of this type
are found, one in a bridge across the Niagara adjacent to the suspension
bridge above described and one across the river Forth at Queens Ferry in
Scotland. The Niagara Bridge is a combination of cast steel and iron. It
was designed by C. C. Schneider and Edmund Hayes. It was built for a
double-track railroad. The total length of the bridge is 910 feet
between the centres of the anchorage piers. The cantilevers rest on two
gigantic steel towers, standing on massive stone piers 39 feet high. The
clear span between the towers is 470 feet, and the height of the bridge,
from the mad rush of waters to the car track is 239 feet.
Messrs Fowler and Baker were the engineers of the Forth railway bridge.
It was begun in 1883 and finished in 1890. It is built nearly all of
steel, and is one of the most stupendous works of the kind. It crosses
two channels formed by the island of Inchgarvie, and each of the channel
spans is 1710 feet in the clear and a clear headway of 150 feet under
the bridge. Three balanced cantilevers are employed, poised on four
gigantic steel tube legs supported on four huge masonry piers. The
height of the bridge above the piers is 330 feet. The cantilever portion
has the appearance of a vast elongated diamond. Steel lattice work of
girders, forms the upper side of the cantilever, while the under side
consists of a hollow curve approaching in form a quadrant of a circle
drawn from the base of the legs or struts to the ends of the cantilever.
Such is the growth of these great bridges with their tremendous spans
across which man is spinning his iron webs, that when seen at night with
a fiery engine pulling its thundering train across in the darkness, one
is reminded of Milton’s description, “over the dark abyss whose boiling
gulf tamely endured a bridge of wondrous length, from Hell continued,
reaching the utmost orb of this frail world.”
The _lighthouses_ of the century, in masonry, do not greatly excel in
general principles those of preceding ones, as at Eddystone, designed by
Smeaton. Nicholas Douglass, however, invented a new system of
dovetailing, and great improvements have been made in the system of
illuminating.
Lighthouses are also distinguished from those of preceding centuries by
the substitution of iron and cast steel for masonry. The first cast-iron
lighthouse was put up at Point Morant, Jamaica, in 1842. Since then they
have taken the form of iron skeleton towers.
One of the latest and most picturesque of lighthouses is that of
Bartholdi’s statue of Liberty enlightening the world, the gift of the
French government to the United States, framed by M. Eiffel, the great
French engineer, and set up by the United States at Bedloe’s Island in
New York harbor. It consists of copper plates on a network of iron.
Although the statue is larger than any in the world of such composite
construction, its success as a lighthouse is not as notable as many
farther seaward.
In _excavating_, _dredging_ and _draining_, the inventions of the
century have been very numerous, but, like numerous advances in the
arts, such inventions, so far as great works are concerned, have
developed from and are closely related to steam engineering.
The making of roads, railroads, canals and tunnels has called forth
thousands of ingenious mechanisms for their accomplishment. A half dozen
men with a steam-power excavator or dredger can in one day perform a
greater extent of work than could a thousand men and a thousand horses
in a single day a few generations ago.
An excavating machine consisting of steel knives to cut the earth, iron
scoops, buckets and dippers to scoop it up, endless chains or cranes to
lift them, actuated by steam, and operated by a single engineer, will
excavate cubic yards of earth by the minute and at a cost of but a few
dollars a day.
Dredging machines of a great variety have been constructed. Drags and
scoops for elevating, and buckets, scrapers and shovels, and rotating
knives to first loosen the earth, suction pumps and pipes, which will
suck great quantities of the loosened earth through pipes to places to
be filled--these and kindred devices are now constantly employed to dig
and excavate, to deepen and widen rivers, to drain lands, to dig canals,
to make harbours, to fill up the waste places and to make courses for
water in desert lands.
Inventions for the excavating of clay, piling and burning it in a crude
state for ballast for railways, are important, especially for those
railways which traverse areas where clay is plentiful, and stones and
gravel are lacking.
Sinking shafts through quicksands by artificially freezing the sand, so
as to form a firm frozen wall immediately around the area where the
shaft is to be sunk, is a recent new idea.
Modern countries especially are waking up to the necessity of good
roads, not only as a necessary means of transportation, but as a
pre-requisite to decent civilisation in all respects. And, therefore,
great activity has been had in the last third of a century in invention
of machines for finishing and repairing roads.
In the matter of sewer construction, regarded now so necessary in all
civilised cities and thickly-settled communities as one of the means of
proper sanitation, great improvements have been made in deep sewerage,
in which the work is largely performed below the surface and with little
obstruction to street traffic.
In connection with excavating and dredging machines, mention should be
made of those great works in the construction of which they bore such
important parts, as drainage and land reclamation, such as is seen in
the modern extensions of land reclamation in Holland, in the Haarlem
lake district in the North part of England, the swamps of Florida and
the drainage of the London district; in modern tunnels such as the
Hoosac in America and the three great ones through the Alps: the Mont
Cenis, St. Gothard, and Arlberg, the work in which developed an entirely
new system of engineering, by the application of newly-discovered
explosives for blasting, new rock-drilling machinery, new
air-compressing machines for driving the drill machines and ventilating
the works, and new hydraulic and pumping machinery for sinking shafts
and pumping out the water.
The great canals, especially the Suez, developed a new system of canal
engineering. Thus by modern inventions of devices for digging and
blasting, dredging and draining and attendant operations, some of the
greatest works of man on earth have been produced, and evinced the
exercise of his highest inventive genius.
If one wishes an ocular demonstration of the wonders wrought in the 19th
century in the several domains of engineering, let him take a Pullman
train across the continent from New York to San Francisco. The distance
is 3,000 miles and the time is four days and four nights. The car in
which the passenger finds himself is a marvel of woodwork and
upholstery--a description of the machinery and processes for producing
which belongs to other arts. The railroad tracks upon which the vehicle
moves are in themselves the results of many inventions. There is the
width of the track, and it was only after a long and expensive contest
that countries and corporations settled upon a uniform gauge. The common
gauge of the leading countries and roads is now 4 feet 8½ inches. A
greater width is known as a broad gauge, a less width as a narrow gauge.
Then as to the rail: first the wooden, then the iron and now the steel,
and all of many shapes and weights. The T-rail invented by Birkensaw in
1820, having two flanges at the top to form a wide berth for the wheels
of the rolling stock, the vertical portion gripped by chairs which are
spiked to the ties, is the best known. Then the frogs, a V-shaped device
by which the wheels are guided from one line of rails to another, when
they form angles with each other; the car wheel made with a flange or
flanges to fit the rail, and the railway gates, ingenious contrivances
that guard railway crossings and are operated automatically by the
passing trains, but more commonly by watchmen. The car may be lighted
with electricity, and as the train dashes along at the rate of 30 to 80
miles an hour, it may be stopped in less than a minute by the touch of
the engineer on an air brake. Is it midwinter and are mountains of snow
encountered? They disappear before the railway snow-plough more quickly
than they came. It passes over bridges, through tunnels, across
viaducts, around the edges of mountain peaks, every mile revealing the
wondrous work of man’s inventive genius for encompassing the earth with
speed, safety and comfort. Over one-half million miles of these railway
tracks are on the earth’s surface to-day!
Not only has the railway superseded horse power in the matter of
transportation to a vast extent, but other modes of transportation are
taking the place of that useful animal. The old-fashioned stage coach,
and then the omnibus, were successively succeeded by the street car
drawn by horses, and then about twenty years ago the horse began to be
withdrawn from that work and the cable substituted.
_Cable transportation_ developed from the art of making iron wire and
steel wire ropes or cables. And endless cables placed underground,
conveyed over rollers and supported on suitable yokes, and driven from a
great central power house, came into use, and to which the cars were
connected by ingeniously contrived lever grips--operated by the driver
on the car. These great cable constructions, expensive as they were,
were found more economical than horse power. In fact, there is no
modernly discovered practical motive power but what has been found less
expensive both as to time and money than horse power. But the cable for
this purpose is now in turn everywhere yielding to electricity, the
great motor next to steam. The overhead cable system for the
transportation of materials of various descriptions in carriers, also
run by a central motor, is still very extensively used. The cable plan
has also been tried with some success in the propelling of canal boats.
_Canals_, themselves, although finding a most serious and in some
localities an entirely destructive rival in the railroad, have grown in
size and importance, and in appliances that have been substituted for
the old-style locks. The latest form of this device is what is known as
the pneumatic balance lock system.
It has been said by Octave Chanute that “Progress in civilisation may
fairly be said to be dependent upon the facilities for men to get about,
upon their intercourse with other men and nations, not only in order to
supply their mutual needs cheaply, but to learn from each other their
wants, their discoveries and their inventions.” Next to the power and
means for moving people, come the immense and wonderful inventions for
lifting and loading, such as cranes and derricks, means for coaling
ships and steamers, for handling and storing the great agricultural
products, grain and hay, and that modern wonder, the _grain elevator_,
that dots the coasts of rivers, lakes and seas, receives the vast stores
of golden grain from thousands of steam cars that come to it laden from
distant plains and discharges it swiftly in mountain loads into vessels
and steamers to be carried to the multitudes across the seas, and to
satisfy that ever-continuing cry, “Give us this day our daily bread.”