Almost entirely of an outdoor character, and necessarily on public exhibition, the engineering achievements of the Nineteenth Century have always been conspicuously in evidence, challenging the admiration of the public eye. They represent man’s attack upon the obstacles presented by nature to his irrepressible spirit of progress. Difficulties apparently insuperable have confronted him, only to melt away under his persistent genius until nothing seems impossible. He has connected continents with the telegraph, has crosshatched the land with railroads, penetrated the bowels of the earth with artesian wells, opened communication between oceans with the Suez Canal, reclaimed territory from the sea in Holland, pierced mountain ranges with tunnels, drained marshes, irrigated deserts, reared lofty structures of masonry and steel, spanned waters with magnificent bridges, opened channel-ways to the sea, built beacons for the mariner, and breakwaters for the storm beaten ship.Probably the most important branch of engineering work is railroad construction, already considered under steam railways. Closely related to the railroad, however, is bridge building, and many of these noble structures hang between heaven and earth, conspicuous monuments of the engineer’s skill.

The Forth Bridge.—This massive structure, of the cantilever type, is shown in Fig. 228. It was begun in 1882 and finished in 1890, and is the largest and most costly viaduct in the world. It is built across the Firth of Forth, and is the most important link in the direct railway communication of the North British Railway, and associated roads, between Edinburgh on the one side, and Perth and Dundee on the other. The total length of the viaduct is 8,296 feet, or nearly 1⁵/₈ miles. The extreme[341]
[342] height of the structure is 361 feet above the water level, and the foundations extend 91 feet below the water level. The two main spans are 1,710 feet, and these both give a clear headway for navigation of 150 feet height. There are over 50,000 tons of steel in the superstructure, and about 140,000 cubic yards of masonry and concrete in the foundation piers. The three main piers consist each of a group of four masonry columns faced with granite, 49 feet in diameter at the top, and 36 feet high, which rest on solid rock, or on concrete carried down in most cases by means of caissons of a maximum diameter of 70 feet to rock or boulder clay.

No intelligent conception of the enormous size of this great structure can be obtained except by comparison. Estimating from the bottom of the masonry piers to the towering heights of the cantilevers, it reaches above the dome of St. Peter’s at Rome, and is only a little short of the height of the greatest of the pyramids of Egypt. The cost of the bridge is given as £3,250,000 or nearly $16,000,000.

The Brooklyn Bridge.—Having for its successful construction and maintenance the same foundation principle upon which the spider builds its web, this magnificent bridge of steel wires spans the East River between New York and Brooklyn, with a total length of 5,989 feet, and in length of span and cost is second only to the great Forth Bridge. It is shown in Fig. 229, and among suspension bridges it ranks first. It has a central span of 1,595¹/₂ feet between the two towers, over which the suspension cables are hung, and has a clear headway beneath of 135 feet. It has two side spans of 930 feet each between the towers and the shore.

The suspension towers stand on two piers founded in the river on solid rock at depths of 78 and 45 feet below high water, and they rise 277 feet above the same level. There are four suspension cables 15¹/₂ inches in diameter, each composed of 5,282 galvanized steel wires, placed side by side, without any twist, and arranged in groups of 19 strands bound up with wire. These cables have a dip in the center of the large span of 128 feet, rest on movable saddles on the top of the towers to allow for slight movement of the cables due to expansion and contraction, and are held down at the shore ends by massive anchorages of masonry. The bridge has a width of 85 feet, and has two roadways, two lines of railway, and a foot way. It was begun in 1876 and opened for traffic in 1883, and its cost was about $15,000,000. It fulfills a great function for the busy metropolis, and it hangs in the air a monument in steel wire to the genius of the Roeblings.

Masonry Bridges.—The largest and finest single span of masonry in America, and believed to be the largest in the world, is to be found about[343]
[344] 9 miles northwest of the city of Washington. It is known as the Washington Aqueduct or Cabin John Bridge, and is seen in Fig. 230. It extends across the small stream known as Cabin John Creek, and carries an aqueduct 9 feet in diameter, that supplies the National Capital with water, its upper surface above the water conduit being formed into a fine roadway. It is 450 feet long. Its span is 220 feet, the height of the roadway above the bed of the stream is 100 feet, and the width of the structure is 20 feet 4 inches. Gen. Montgomery C. Meigs was the engineer in charge of its construction. It was begun in 1857 and finished in 1864, with the exception of the parapet walls of the roadway, which were added in 1872-3. Its cost was $254,000. Only one other masonry arch has ever been built which equalled this in size. The Trezzo Bridge, built in the fourteenth century, over the Adda in North Italy, and subsequently destroyed, is said to have had a span of 251 feet, but the Washington Aqueduct Bridge at Cabin John is a noble work in masonry, and when standing beneath its majestic sweep, and viewing the regular courses of masonry hanging nearly a hundred feet high in the air, and springing more than a hundred feet from the embankment upon either side, one loses sight of the principles of the arch, and the fear that the mass may fall upon him gives way to the impression that nature has bowed to the genius of man, and suspended the law of gravity.

Among the patents granted for bridges the most important are those relating to the cantilever type, among which may be mentioned those to Bender, Latrobe, and Smith, No. 141,310, July 29, 1873; Eads, No. 142,378 to 142,382, September 2, 1873, and Clarke, No. 504,559, September 5, 1893.Caissons.—For submarine explorations the ancient diving bell, which was said to have been used more than 2,000 years ago, has given place to diving armor, while for more extensive local work the pneumatic caisson is employed. The latter was invented by M. Triger, a French engineer, in 1841. An early example of it is also given in Cochrane’s British patent No. 3,226, of 1861. It consists of a vertical cylinder divided into compartments, its lower open end resting on the river bottom. Compressed air forced into the lower compartment forces the water back, while the men are at work, the intermediate chamber forming an air lock, by which entrance to, or egress from, the lower working chamber is obtained. The pneumatic caissons of Eads (patents Nos. 123,002, January 23, 1872, and 123,685, February 13, 1872) and Flad (patent No. 303,830, August 19, 1884) are modern applications of the same principle. The sinking of shafts through quicksand, by artificially freezing the same and then treating it as solid material, is an ingenious modern method shown in patents to Poetsch, No. 300,891, June 24, 1884; and Smith, No. 371,389, October 11, 1887.Tunnels.—Less conspicuous than bridges, by virtue of their underground character, but none the less important, are these mole-like means of communication. Especially difficult of construction for the reason that the nature of the soil or rock is largely unknown, and for the reason also that the work may have to encounter faults in rocks, and springs or quicksands in the earth; nevertheless the demands of the railroads for shortening the distance of travel and economizing time have stimulated the engineer to expend millions of dollars in piercing the earth with these great underground passageways.

The Mont Cenis Tunnel was constructed to establish railway communication between France and Italy through the Alps. It was begun in 1857, and after having been in progress of construction for thirteen years, was opened for traffic in 1871. This tunnel was commenced by hand borings, being for the most part through solid rock, and its progress up to 1862 was so slow that it was estimated that thirty years would be required for its construction. Its earlier completion was due to the introduction of rock drills operated by compressed air, which trebled the rate of advance, and which device made a new epoch in all rock-boring and mining operations. This tunnel was cut from both ends at the same time, and so accurate were the surveys in establishing the alignment of the two headings through the mountain mass, that, although the tunnel was more than 7¹/₂ miles long, when the two headings came together in the middle, only a difference of one foot in level existed between them. When it is remembered that most of the 7¹/₂ miles of tunnel was cut through solid rock, by boring and blasting, the immensity of the undertaking can be appreciated. As completed the tunnel is 8 miles long, and wide enough for a double track railway.

The St. Gothard Tunnel is another tunnel through the Alps, which involved even a longer and deeper cut through the mountains than the Mont Cenis Tunnel. This is 9¹/₄ miles long, and it was begun in 1872, the headings joined in 1880, and the tunnel opened for traffic in 1882. Although by far the largest undertaking yet made, the improvement in rock-boring machinery enabled it to be constructed much more rapidly and at less expense.

The Arlberg is still another Alpine tunnel. It is 6¹/₂ miles long, was commenced in 1880, and opened for traffic in 1884.

Tunneling under rivers presents many more difficulties than driving through the hardest rock. This is so by reason of the inflow of water. Among successful tunnels of this kind may be named the Mersey and Severn tunnels in England, opened in 1886, and the St. Clair tunnel between the United States and Canada. The histories of the abandoned Detroit and Hudson river tunnels are object lessons of the difficulties encountered in this class of work.

An important engineering invention for tunneling through silt or soft soil is the so-called “shield.” This was first employed by the engineer Brunel in the construction of the Thames tunnel, which was begun in 1825 and opened as a thoroughfare in 1843. The shield, as now used, is a sort of a cylinder or sleeve as large as the tunnel, which sleeve, as the excavation proceeds in front of it, is forced ahead to act both as a ring-shaped cutter and a protection to the workmen, its advance being effected by powerful hydraulic jacks or screws which find a back bearing against the completed wall of the tunnel. As the digging proceeds the shield is advanced, and a section of tunnel is built behind it which, in turn, furnishes a bearing for the jacks in the further advance of the shield.This latter improvement was the invention of the late Alfred E. Beach, of the Scientific American, and was covered by him in patent No. 91,071, June 8, 1869, and was used in driving the experimental pneumatic subway constructed by him under Broadway, New York, in 1868-9, and also in the St. Clair River tunnel and the unfinished Hudson River tunnel and other works.

Subsequent improvements made upon the shield by J. H. Greathead of England and covered by him in United States patents Nos. 360,959, April 12, 1887; and 432,871, July 22, 1890, have greatly added to the value and efficiency of this device, and made it one of the leading instrumentalities in tunnel construction.Suez Canal.—It is said that the undertaking of connecting the Mediterranean and Red Seas was considered as long ago as the time of Herodotus, and a small channel appears to have been opened twenty-five centuries ago, but was subsequently abandoned. In 1847 the subject was again taken up for serious consideration, the work begun in 1860, and finished in 1869, at a cost of £20,500,000, or more than a hundred million dollars. The canal starts at Port Said, on the Mediterranean, a view of which with its ships of all nations and the canal reaching far away in the distance is seen in Fig. 231. The canal extends nearly due south to Suez on the Red Sea, a distance of about 100 miles, through barren wastes of sand and an occasional lake. It was originally formed with a bottom width of 72 feet, spreading out to 196 to 328 feet at the top, and of a depth of 26 feet, but has since been increased in transverse dimension to accommodate the great increase in travel.

Sixty great dredges were employed on the work, and the dredged material was discharged in chutes on to the bank. The canal was the work of M. De Lesseps, the eminent French engineer, and has proved a great success from both an engineering and financial standpoint. The stock is mainly held in England, having been bought from the Khedive of Egypt. In 1898 the ships passing through the canal during the year reached the remarkable number of 3,503. The rate of tolls is 10 francs (about $2) per net ton. The gross tonnage of ships passing through in 1898 was 12,962,632, the net tonnage 9,238,603. The total receipts for the year were 87,906,255 francs (about $17,500,000), and the net profit 63,441,987 francs (about $12,500,000). An average size ocean liner pays about $5,000 for the privilege of sailing through this great ditch. Admiral Dewey’s ship, the “Olympia,” returning from the Philippines, paid for her toll $3,516.04, and the “Chicago,” $3,165.95. Going the other way, our supply ship “Alexander” paid $4,107.99, while the “Glacier” paid $5,052.38. Ships making the passage through the canal move slowly on[348]
[349] account of the washing of the banks, about 22 hours being required, but the shortening of the travel of ships going east and west, and the saving of life, property, and time, involved in avoiding the circuitous and stormy passage around the Cape of Good Hope, has been of incalculable benefit to the world.

With the construction of canals and harbors, great improvements have been made in dredges. Some of these are of the clam-shell type, some employ the scoop and lever, others an endless series of buckets. An example of the latter, used on the Panama Canal, is seen in Fig. 232. Still another form, and the most recent if not the most important is the hydraulic dredger, which, by rotating cutters, stirs and cuts the mud and silt, and by powerful suction pumps and immense tubes draws up the semi-fluid mass and sends it to suitable points of discharge. The best known of the latter type is the Bowers hydraulic dredge, covered by many patents, of which Nos. 318,859 and 318,860, May 26, 1885; 388,253, August 21, 1888; and 484,763, October 18, 1892, are the most important.For surface excavations in solid earth the Lidgerwood Cableway is an important and labor saving device. A track cable is stretched from two distant towers, and a bucket holding well on to a ton of earth is made to travel on a trolley running on said cable track, rising at one end out of the excavation, and dumping at the other end to fill in the excavation as the cutting progresses, all in a continuous and economical manner. This device is made under the patent to M. W. Locke, No. 295,776, March 25, 1884, and comprehends many subsequent improvements patented by Miller, Delaney, North and others. The Chicago Drainage Canal is a work just completed, which largely employed these devices. This canal was designed to connect the Chicago River with the Mississippi River, so as to send the sewage of Chicago down the Mississippi instead of into Lake Michigan. Although it cost $33,000,000 and required seven years for completion, the labor-saving cableways greatly cheapened its cost and shortened the time of its construction.Among the leading inventions relating to canal construction may be mentioned the bear-trap canal-lock gate (patents Nos. 229,682, 236,488 and 552,063), and the Dutton pneumatic lift locks. The latter provide ease and rapidity of action by a principle of balancing locks in pairs, and are covered by his patent No. 457,528, August 11, 1891, and others of subsequent date.Artesian Wells represent an important branch of engineering work, and they are so called from the province of Artois, in France, where they have for a long time been in use. Extending several thousand feet into the subterranean chambers of the earth, they have brought abundant water supply to the surface all over the world, from the desert sands of Sahara to the hotels of the modern city; they have contributed oil and gas in incredible quantities to supply light and heat, and have made valuable additions to the salt supply of the world.

They are driven by reciprocating a ponderous chisel-shaped drill within an iron tube, six inches more or less in diameter, which is built up in sections, and moved down as the cutting descends. The drill is reciprocated by a suspending rope from machinery in a derrick, and in order to give a hammer-like blow to the chisel a pair of ponderous iron links coupled together like those of a chain, and called a “drill jar” connect the drill to the rope. As the sections of the link slide over each other they come together with a hammer blow at the moment of lifting that dislodges the drill from the rock, and on the descending movement they come together with a hammering blow immediately after the drill touches the rock to drive it into the same. The first United States patent for a drill jar is that to Morris, No. 2,243, September 4, 1841. When an oil well ceases to flow, it is rejuvenated by being “shot,” which is quite contrary to the ordinary conception of prolonging life. For this purpose a dynamite cartridge is exploded at the lower end of the well, which shatters the rock, and, in opening up new channels of flow for the oil, renews the yield. Many patented inventions have been made in the field of well boring, and the discovery of coal oil in the United States in 1859 has developed a great industry and built up enormous fortunes. The amount of petroleum produced in the United States in 1896 was 60,960,361 barrels, the largest yield on record. In 1897 the amount was 60,568,081 barrels.

Of less consequence than the artesian well, but finding many useful applications, is the drive well. A metal tube with a perforated lower end is driven down by hammers into the ground, and furnishes a quick and cheap source of water supply. This was invented by Col. Green in 1861, in meeting the necessities of his military camp during the civil war, and was patented by him January 14, 1868, No. 73,425.Rock Drills.—In mining and tunneling through rock, the rock drill has been the implement of paramount importance and utility. For boring by rotary action the diamond drill is most effective. This uses bits set with diamonds which, by their extreme hardness, cut through the most refractory rock with great rapidity. It was invented by Hermann and patented by him in France, June 3, 1854.

More important, however, is the compressed air rock drill, in which a piston has the drill bit directly on its piston rod and cuts by a reciprocating action. The piston is actuated by compressed air admitted alternately to its opposite sides in an automatic manner by valves. The compressed air conveyed to the drill in the tunnel or mine not only operates the drill, but helps to ventilate the tunnel. As early as 1849 Clarke and Motley, in England, invented a machine drill, and in 1851 Fowle devised a similar machine, having the drill attached directly to the piston cross head. The Hoosac and Mont Cenis tunnels greatly stimulated invention in this field, and among the notable drills of this class may be named the Burleigh, Ingersoll, and Sergeant. The Burleigh drill was brought out in 1866, and was covered by patents Nos. 52,960, 52,961 and 59,960 of that year, and 113,850 of 1871, and the Ingersoll drill, by patents No. 112,254, and No. 120,279, of 1871.

Blasting.—The discovery of nitro-glycerine in 1846, followed by its convenient commercial preparation in the form of dynamite, gave a great impetus to blasting. Notable as the largest operation of the kind in the century is the blowing up of Flood Rock, in the path of commerce between New York City and Long Island Sound. The dangerous character of this and other rocks in this vicinity gave long ago to this channel the significant name of Hell Gate. The undermining of the rocks by shafts and galleries is seen in Fig. 233, and the final blowing up of the same in a single blast was the culmination of a series of similar operations at this point tending to safer navigation. On October 10, 1885, 40,000 cartridges, containing 75,000 pounds of dynamite and 240,000 pounds of rack-a-rock, were, by the touching of a button and the closing of an electric circuit, simultaneously exploded. In the twinkling of an eye nine acres of solid rock were shattered into fragments by the prodigious force, and a vast upheaval of water 1,400 feet long, 800 feet wide, and 200 feet high, sprang into the air in tangled and gigantic fountains. As the termination of the most stupendous piece of engineering of the kind the world has ever seen, and with spectacular features fitting the enormous expense of $1,000,000, which the work cost, this final scene put an end to the menaces of Flood Rock, and wiped out of existence the worst dangers of Hell Gate.

Mississippi Jetties.—The broad bar and shallow waters at the mouth of the Mississippi involved such an obstruction to commerce that in 1872 it received the attention of Congress, resulting in the building, by Capt. Eads, of the celebrated jetties. They were begun in 1875 and finished in 1879, and cost $5,250,000. The channel obtained was 30 feet deep and 200 feet wide. Its construction involved the building across the bar and out into the Gulf of Mexico two long reaches of parallel embankments, called jetties. This was effected by sinking mattresses of willow branches bound together and weighted with stone. These were laid in four layers, and when submerged, and resting upon the bottom, were covered with a layer of loose stone, and this in turn was surmounted with a capping of concrete blocks, as seen in cross section in Fig. 234. These jetties so concentrated the flow of waters into a narrow channel as to cause its increased velocity to wash out the mud and silt and deepen the channel. The immensity of the work may be measured by the quantity of material used in its construction, which included 6,000,000 cubic yards of willow mattresses, 1,000,000 cubic yards of stone, 13,000,000 feet (board measure) of lumber, and 8,000,000 cubic yards of concrete. The mattresses were laid 35 to 50 feet wide at the bottom, which width was considerably increased by the superimposed layer of stone, and the jetties extended 2¹/₄ miles into the sea. Their influence upon commerce is indicated by the fact that before their construction the annual grain export from New Orleans was less than half a million bushels, and in 1880, the year following their completion, it was increased to 14,000,000 bushels.

High Buildings.—A distinct feature of modern architecture is the enormously tall steel frame building known as the “sky scraper.” The increasing value of city lots first brought about the vertical extension of buildings to a greater number of stories, and the necessity for making them fireproof, coupled with the desire to avoid loss of interior space, due to thick walls at the base, made a demand for a different style of architecture. To meet this a skeleton frame of steel is bolted together in unitary structure, the floors being all carried on the steel frame, and the outer masonry walls being relatively thin, and carrying only their own weight. In Fig. 235 is shown an example of the interior structure of such a building. The vertical columns are erected upon a very firm foundation, and to them are bolted, on the floor levels, horizontal I-beams and girders, stayed by tie rods, which I-beams receive between them hollow fireproof tile to form the floor. The outer masonry walls are built around the skeleton frame, as seen in Fig. 236, and the details of connections for the floor members appear in Fig. 237.

The construction of iron buildings began about the middle of the century. In 1845 Peter Cooper erected the largest rolling mill at that time in the United States for making railroad iron, and at this mill wrought iron beams for fireproof buildings were first rolled. In the building of the Cooper Institute in New York City in 1857 he was the first to employ such beams with brick arches to support the floors. The unifying of the iron work into an integral skeleton frame, for relieving the side walls of the weight of the floors is, however, a comparatively recent development, and this has so raised the height of the modern office building as to cause it to impress the observer as an obelisk rather than a place of habitation. An earthquake-proof steel palace for the Crown Prince of Japan is one of the modern applications of steel in architecture. It is being built by American engineers, and is to cost $3,000,000.

Eiffel Tower.—Loftiest among the high structures of the world, and significant as indicating the possibilities of iron construction, the Eiffel Tower of the Paris Exposition of 1889 was a distinct achievement in the engineering world. It is seen in Fig. 238. It is 984 feet high, and 410 feet across its foundation, and has a supporting base of four independent lattice work piers. In the top was constructed a scientific laboratory surmounted by a lantern containing a powerful electric light. The total weight of iron in the structure is about 7,000 tons, the weight of the rivets alone being 450 tons, and the total number of them 2,500,000. The level of the first story is marked by a bold frieze, on the panels of which, around all four faces, were inscribed in gigantic letters of gold the names of the famous Frenchmen of the century. The summit of the tower was reached by staircases containing 1,793 steps, and by hydraulic elevators running in four stages. The cost of this structure was nearly $1,000,000.

Washington’s Monument.—Next in height to the Eiffel Tower, and being, in fact, the tallest masonry structure in the world, this noble obelisk, by its simplicity, boldness and solidity, challenges the admiration of every visitor, and gratifies the pride of every patriot. It is seen in Fig. 239, and is 555 feet 5¹/₂ inches high, 55 feet square at the base, and 34 feet square at the top. The walls are 15 feet thick at the base, and 18 inches at the top, and its summit is reached by an internal winding staircase and a central elevator. At the height of 504 feet the walls are pierced with port holes, from which a magnificent view is had of the capital city and surrounding country. The summit is crowned with a cap of aluminum, inscribed Laus Deo. The foundation of rock and cement is 36 feet deep and 126 feet square, and the total cost of the monument was $1,300,000. The corner stone was laid in 1848. In 1855 the work was discontinued at the height of 152 feet, from lack of funds. In 1878 it was resumed by appropriation from Congress, and completed and dedicated in 1885, under the direction of Col. Thomas L. Casey, of the United States Corps of Engineers.The Capitol Building.—Representing the heart of the great American Republic, and overlooking its Capital City, this grand building, shown in Fig. 240, is a poem in architecture. Massive, symmetrical and harmonious, its highest point reaches 307¹/₂ feet above the plaza on the east. It is 751 feet 4 inches long, 350 feet wide, and the walls of the building proper cover 3¹/₂ acres. Crowning the center of the building is the imposing dome of iron, surmounted by a lantern, and above this is the bronze statue of Freedom, 19 feet 6 inches high, and[358]
[359] weighing 14,985 pounds, the latter being set in place December 2, 1863. The dome is 135 feet 5 inches in diameter at the base, and the open space of the rotunda within is 96 feet in diameter and 180 feet high.

The corner stone of the original building was laid in 1793 by Washington. The first session of Congress held there was in 1800, while the building was still incomplete. The original building was finished in 1811. In 1814 it was partly burned by the British. In 1815 reconstruction was begun, and completed in 1827. In 1850 Congress passed an act authorizing the extension of the Capitol, which resulted in the building of the north and south wings, containing the present Senate Chamber and Hall of the House of Representatives. The corner stones of the extension were laid by President Fillmore in 1851, Daniel Webster being the orator of the occasion, and the wings were finished in 1867. Since this time handsome additions in the shape of marble terraces on the west front have added greatly to the beauty and apparent size of the building.

It is not possible to give anything like an adequate review of the engineering inventions and achievements of the Nineteenth Century in a single chapter, and only the most noteworthy have been mentioned. The modern life of the world, however, has been replete with the resourceful expedients of the engineer, and the ingenious instrumentalities invented by him to carry out his plans. There have been about 1,000 patents granted for bridges, about 2,500 for excavating apparatus, and about 1,500 for hydraulic engineering. In mining the safety-lamp of Sir Humphrey Davy, in 1815, has been followed by stamp mills, rock-drills, derricks, and hoisting and lowering apparatus, and lately by hydraulic mining apparatus, by which a stream of water under high pressure is made to wash away a mountain side. Apparatus for loading and unloading, pneumatic conveyors, great systems of irrigation, lighthouses, breakwaters, pile drivers, dry-docks, ship railways, road-making apparatus, fire escapes, fireproof buildings, water towers, and filtration plants have been devised, constructed and utilized. Many gigantic schemes, already begun, still await successful completion, among which may be named the draining of the Zuyder Zee, the Siberian railway, the Panama and Nicaraguan Canals, the Simplon tunnel, the new East River Bridge, and the Rapid Transit Tunnel under New York City; while a bridge or tunnel across the English Channel, a ship canal for France, connecting the Bay of Biscay with the Mediterranean, a tunnel under the Straits of Gibraltar, and a ship canal connecting the great lakes with the Gulf of Mexico, are among the possible achievements which challenge the engineer of the Twentieth Century.