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entire structure, and the two arms of the can upon 12 iron plate-girders 24 feet deep and 36 tilever are different in length and in details of feet long, resting in turn on 18 15-inch l-beams construction. The cantilever type of high- through which the anchorage-rods pass in such level bridges is a development of the use of a way that the pressure is distributed evenly cast-steel, which combines with rigidity a ten over the entire mass of masonry. The maxisile elasticity that enables it to resist lateral mum uplifting force of the cantilevers is 678,strains to a certain degree. Like the suspen. 000 pounds, or only about one third of the sion-bridge, the cantilever span can be carried weight of the piers. over places where, as in the Niagara chasm, it After the towers were built, the shore arms is impossible to erect temporary supports. The were constructed by the aid of temporary two gigantic steel towers which bear up the structures, in the usual way. After they were cantilevers of the Niagara bridge are 132 feet completed and attached to the anchorages, the high, and rest on stone piers 39 feet high. river arms were built out over the river, one They are composed of four columns of plates panel at a time, by means of huge traveling and angles riveted together, braced with hori- steam-derricks. When each panel was conzontal struts and ties. They converge upward structed and braced, the traveler was moved with a batter of 1 in 24 in the direction of the forward and the next panel erected. The inlength of the bridge and 1 in 8 at right angles termediate 120-foot span was specially designed to the middle line of the bridge. The canti- with bottom compression members so that it levers are each 395 feet in length. A space of also could be built out from the end of each 120 feet between the river ends of the canti arm by the aid of temporary stays, which levers is spanned by a girder resting on the were removed when the two halves of the extremities of the arms. The total length of girder were fitted together in the middle. the bridge is 910 feet between the centers of The bridge is designed to bear a running the anchorage-piers. The clear span between load of a ton per lineal foot, that being one the towers is 470 feet. The height of the fifth of the calculated ultimate resistance, and bridge is 239 feet from the surface of the river for a wind pressure of thirty pounds per square to the rail. The cantilevers are composed of foot on twice the exposed face of the truss, two trusses, 28 feet apart, having a depth of foor, and train. 56 feet at the towers, 26 feet at the extremi Forth Railway-Bridge. The completion of the ties of the river arms, and 21 feet at the shore Niagara cantilever bridge lends interest to a ends. The materials used in the bridge are description of the one over the river Forth at steel and wronght-iron, the former for the tow. Queens Ferry, in Scotland, which was begun ers and the lower chords, center posts, and all in 1883. The engineers of Great Britain, to the pins, and the latter for all the tension mem whom the development of the cantilever prinbers. The steel pins connecting the members ciple is due, have never taken kindly to the fit into the bored holes with the utmost ac- suspension principle, just as they are in gencaracy. The lower chords and center posts eral skeptical of the stability of the lighter are latticed channel-plates. The upper chords structures which American engineers design are heavy eye-bars. A compression member for equal stresses. Yet, after condemning is packed between the chords of the shore the principle for a whole generation, while the arras. The shore ends of the beams are an- Niagara suspension-bridge stood as a practical chored to masonry abutments by short links, demonstration of its soundness, at last Sir which serve also as expansion-joints. Joints Thomas Bouch adopted the American idea in are provided also at the connection of the in- his design for the projected bridge over the termediate span with the river ends, to allow Forth. The river was to be bridged by two for contraction and expansion due to changes suspension spans, with towers nearly 600 feet of temperature. The floor-beams are wrought- high, one on each bank and two on the island iron plates and angles, 4 feet deep, riveted be- of Inchgarvie in the middle of the estuary. tween the vertical posts. On these rest four The foundations were already dug, when the lines of stringers, consisting of plate-girders 2} Tay bridge disaster first brought to the knowl. feet deep. The width of the floor is 32 feet, à edge of engineers facts relating to the intensity plank walk and iron railing at the side of the of wind-strains which meteorologists bad altracks being supported by the white-oak ties, ready published to the world. The designs one half of which project beyond the tracks for the suspension-bridge, whose author was for the purpose. Each column of the towers the designer also of the collapsed Tay structstands on a limestone pier, 12 feet square at ure, were discarded. Fowler and Baker, the the top and battering 1 in 24. The piers are new engineers, drew plans for a cantilever connected by walls 34 feet wide at top. The truss double-span bridge, all of steel, which courses of the piers are 2 feet deep. The will be the most stupendous structure of its foundations are a solidified mass of bowlders, kind. The material is tested for an ultimate béton, and cement, 20 by 45 feet and 8 feet resistance of thirty tons per square inch in tendeep under each pair of piers. The anchorage- sion, and thirty-four tons in compression, and piers are 11 by 374 feet under the coping, and the structure is planned to sustain four times consist of blocks of masonry, each measuring the combined strain of a wind pressure of 460 eubio yards and weighing 1,000 tons, raised fifty-six pounds to the square foot and a maxi

mum running load of two tons to the foot, or France, is even loftier than the lately com3,400 tons on a span. The breadth to be pleted Kinzua bridge in Pennsylvania. The spanned in the Forth is not much more than French viaduct has a great arch in the center. half that of the Tay at Dundee, where the new The height from the bed of the river to the bridge, which will cost about £750,000, is rail is 413 feet, while in the Kinzua valley viamaking rapid progress and is expected to be duct the level of the rail is 301 feet above the finished in 1885. But the channels on the two stream-bed. In length the French structure sides of the island of Inchgarvie are about 200 is 1,880 feet, or 171 feet less than the other. feet deep, and must therefore be crossed by American Transcontinental Railroads.—The comspanning the entire breadth of some 1,600 feet pletion of the Northern Pacific railroad in Ocon each side. Three balanced cantilevers are tober gives the United States three or propsufficient to accomplish this. Two of them erly four great transcontinental lines, while rest on piers erected at the edge of the channel two more are far advanced in construction. on each side of the river, and one on the The Atchison, Topeka, and Santa Fé, the island. The cantilever has the shape of an last link of which was finished two months elongated diamond. There are four masonry before the Northern Pacific, is the fonrth to piers to support the four gigantic legs on which reach completion. The Northern Pacific has are poised the balancing arms, which extend its eastern terminus at Duluth, where it con675 feet on each side of the base. The uprights nects with land and water routes to the seaconverge upward, being 120 feet apart at the board. The road bas recently been extended base, 33 feet at the top, where the middle eastward to Superior City, with the intention point of the girder rests on the ends of the of ultimately crossing the Sault Ste. Marie and legs. The middle cantilever is longer than the finding an outlet on the seaboard by one of other two, its base being 270 feet long, while the new trunk lines. The western terminus theirs are 155 feet. The four legs are steel and the difficult section across the Cascade tubes, 12 inches in diameter and 320 feet range were changed from the original plan, long. The height of the bridge above the owing to the combination under the Villard piers is 330 feet. While a lattice-girder forms management with the Oregon company. Inthe upper side of the cantilever, the under side stead of terminating at Puget Sound, the Paof the enormous truss is a hollow curve, ap- cific section follows Columbia river down to proaching in form a quadrant of a circle, drawn Portland. The first of the transcontinental from the base of the legs, or struts, to the ends lines that was built was the Union Pacific of the cantilever. The ends of the beams do from Omaha to Ogden, continued by the Cennot touch each other within 350 feet. The in- tral Pacific, to San Francisco. This road was termediate space is bridged by lattice-girders chartered in 1863 and completed in 1869. The resting on the ends of the arms. On the shore Southern Pacific, in connection with the Texas sides of the outside cantilevers the weight of and Pacific, forms a third transcontinental these girders is counterpoised by an equal route. The eastern terminus of the Southern weight of metal. The bridge will present the Pacific railroad is at Galveston, and that of appearance of two distended arches and a the Texas and Pacific at New Orleans. The half-arch at each end. The shore sections will Southern Pacific railroad has recently supconsist of girders resting on stone piers. There plied the link which gives it a northern terwill be eight piers within high-water mark and minus at Vicksburg in the direction of its two on land, on the south side, and six on the natural ocean outlet at Savannah. It apnorth side, all on land.

proaches the Pacific ocean near San Diego, Garabit Viaduct.—A bridge, begon in 1881 which is its natural terminus, but it is now and to be finished in 1884, which is intended carried up through California to San Francisco. to carry a railroad over a river at Garabit, The Atlantic and Pacific, called sometimes the

thirty-fifth parallel road (as the last mentioned is called the thirty - second parallel route), terminates through its continuation, the St.Louis and San Francisco road, at St. Louis. It emerges on the Pacific coast at the same place as the Southern Pacific, and uses its prolongation up the coast to meet the ocean commerce at San Francisco. The Atchison, Topeka, and Santa Fé, which line was completed in 1883, forms with the Sonora railroad, lately acquired

GARABIT VIADUCT.

by purchase, running south ward through Mexi- gentine Republic is much more feasible as a co to Guaymas, on the Gulf of California, a fifth work of engineering, and commercially more transcontinental line, connecting with the East- promising. The project was under consideraern railroads at Kansas City. The Canadian Pa- tion at the time when Meiggs carried out his cific is rapidly approaching completion. South stupendous works. A convention between the of the United States there are, besides the Pan- two governments has been in existence many ama railroad, three Nexican interoceanic lines years, but they do not seem to desire such close chartered and partly constructed. The most commercial communication. The distance benortherly crosses Tampico to San Blas and is tween the two capitals in a direct line is only called the Mexican Central. The Mexican Na- 375 miles. The dangers from water and an tional railroad crosses from Vera Cruz, by way exuberent vegetation, which are found in the of the city of Mexico, to Manzanillo. The third Brazilian route, are here absent. There was no is the line across the Isthmus of Tehuantepec, known practicable pass in the Andes, but no which was begun with the aid of subsidies by technical examination of the mountains had an American company, but became forfeit by yet been made. Lately a gap in the chain has lapse of the term stipulated for completion, been discovered farther south, in Northern and was confiscated and carried on by thé Patagonia, which would afford an easy passage. Mexican Government.

EPIDEMIC DISEASES IN 1883. With the exThe southern route for a Pacific railway now ception of cholera and yellow fever, there has followed by the Southern Pacific, the Atchi- been no wide-spread epidemic of disease durson, Topeka, and Santa Fé, and the new Atlan- ing the year; but these have been manifested tic and Pacific lines, was proposed when the with their usual virulence and activity. Euproject of a transcontinental railway was first rope and the United States escaped an epidemic, ander discussion, but was rejected by Con- but Egypt suffered almost as much from the gress. It has the advantage of avoiding the devastations of cholera as from the effects of elevations north of Colorado and in the Ne- her civil war, and certain towns in Mexico were Fada plateau. The Northern Pacific, where it almost depopulated by yellow fever and the crosses the Rocky mountains, is a remarkable resulting panic. . Concerning the cholera in example of railroad engineering. There is a Egypt, it is officially stated that the deathis gradual ascent on the western side through a from the disease were in excess of 48,000, and magnificent forest-region to Clark's Fork. At probably reached 50,000. This epidemic first Missoula, in this valley, it assumes the charac- appeared at Damietta, on the 24th of June, ter of a mountain railway, which is preserved 1883. The city itself had a population of up to the point where it emerges in the valley about 32,000. On the 27th of June cholera of the Yellowstone. It crosses the summit was reported from Port Said, and on the 30th range, the Cascades, at Mullen Pass, through a of June at Samanoud, but it was not until tunnel nearly 4,000 feet in length, at an eleva- the 15th of July that the disease reached tion of 6,560 feet. The descent on the oppo- Cairo. A great panio prevailed throughout site slope is by moderate gradients through Egypt, and on the earliest report of the existthe valleys of the head-waters of the Missouri, ence of cholera at Damietta, the people fled the Jefferson, the Madison, the East and West in great numbers; a majority of them departGallatin, and finally the Yellowstone, which it ing for Turkey. The Porte required all refuleaves at Glendive.

gees from Egypt to undergo quarantine, either The construction of a transcontinental rail. at Beirut or Bourla at the

entrance of the Bay road across South America is an engineering of Smyrna. Consul-General Heap reported to problem the conditions of which are entirely the State Department from Constantinople, on different from those of the North American the 21st of July, that “the limited accommoroutes. Henry Meiggs, when building in Peru dations at both places were enlarged by the his first Andes railroad, till then the most mag- erection of temporary wooden barracks and nificent mountain railway in the world, which tents, but the panic-stricken refugees from ascends to altitudes as great as Mont Blanc, in Alexandria came in such numbers that these which the barometric pressure is only 400 milli- structures soon became insufficient to accommetres, and fire will scarcely burn, intended it modate such crowds, and as each day brought as a link in a railroad across the continent. fresh arrivals, the sufferings of these people This work of genius was thrown into the shade from exposure to the burning sun and the by bis Lima-Oroya railroad, which ascends on chilling night dews became very great, and each side through 44 tunnels and over dizzy threatened to create the very evil it was the viaducts, to the summit-level in the Cima- intention to guard against. Those arriving at Jalera tunnel, 1,860 metres long and 4,769 Beirut were the greatest sufferers, and the metres above the level of the sea. The project Turkish authorities were finally compelled to of a transcontinental railway was not only pre- telegraph to Alexandria, to give warning that mature, but the location of the route by Meiggs no more refugees could be received, or would was through countries which, though possess- be allowed to land." ing onlimited natural resources, were socially Sanitary cordons were established in a somebackward. An interoceanic road between the what desultory manner by the local authorities Dore progressive states of Chili and the Ar- of each place, from time to time, and such as were thought necessary were finally made of cargoes from Egypt and of passengers; and effective by the British Government. Many it is probable that the failure of the cholera to of the cordons had been established to protect spread to Europe is due, first, to the early quarplaces which were either infected at the time antine measures instituted against it, and, secor subsequently became infected, were then ond, to the energetic policy of the British Gov. abolished, they being no longer of any use, and ernment when it was discovered that the Egypthe British Government directed the enforce- tians were either powerless or incompetent to ment of sanitary measures by the troops then institute proper sanitary measures themselves. in Egypt.

Owing to the large quantities of rags annually The following extract from a report to the exported from Egypt to the United States by State Department, by United States Consul- way of England, it was felt by our GovernGeneral G. P. Pomeroy, stationed at Cairo, ment that great danger existed in the unreunder date of August 16th, will show the ener- stricted importation of infected rags, and sani. getic measures adopted :

tary inspectors were appointed in Liverpool At a recent interview with Surgeon-General Hunter, and London, to inspect the cargoes of vessels who was sent to Egypt by the English Foreign Office departing for the United States, and to give as medical adviser to the Egyptian Government, I notification by telegraph of the departure of learned a few facts, which I will here recount. This gentleman, with medical assistants, has just returned infected goods. Collectors of customs were to Cairo from a tour of inspection of the infected dis- forbidden to allow the entry of Egyptian rags tricts in Lower Egypt, of which the most important until the municipal health officer of the port towns are Damietta, Mansourab, Samanoud, Zagazig, where the entry was to be made should give a Kafr-Zayat, Mahala-Kybir, Tanta, and Benha. Sur certificate that in his opinion no danger need geon-General Hunter remarked that, with the aid of Sir Edward Malet, he communicated to the Minister be apprehended from so doing. This almost of the Interior a decided wish to see promptly exe- stopped the importation of Egyptian rags for cuted in Cairo, and throughout all the infected dis- some months, and steamships declined to retricts, the cleaning of the mosques, streets, and cemer ceive suspected rags as freight. It is now prolcast one metre under the ground, to cover them with posed that American shippers of rags shall have quicklime, and to destroy by fire the small houses them properly disinfected before shipment, and tainted with the malady, and the pestilential or nox- to that end a sanitary inspector, acting under ious air by which it is produced. In this matter, it is the direction of the United States consul, has necessary to state, the Arab peoplo all through the been appointed, and stationed at Alexandria

, a considerable opposition, which was fortunately whose duty it is to see that the rags have been silenced by naming, as delegates for executing these thoroughly boiled before baling. Machinery on measures, notables, Arab doctors, and employés of a large scale has been shipped to Alexandria by the different government local administrations. Surgeon-General Hunter also informed me that the Engn of the United States, whereby the boiling and

one of the principal paper-manufacturing firms native authorities, has concluded to form here, as in subsequent drying may be accomplished with India, a permanent Sanitary Commission, which will but little loss of time. From a scientific point be composed, in the beginning, of eight officers and of view, the cholera epidemic in Egypt does not Board (intendancy), who are experienced in the study. The early cordons were too inefficiently con

to have afforded any permanent lesson. plete charge and management, in this land, of all pub- ducted to be of material service in settling the fic sanitary measures.

question as to the prevention of its spread, and Consul-General Pomeroy expressed his opin- the several commissions sent by France and ion that the chief cause of the present” cessa- Germany respectively do not appear to have tion of cholera in Cairo, and some other towns, conclusively settled the causation of the disis to be attributed to the very high rise of the The German Commission, headed by Nile, which has very lately filled with fresh Prof. Koch, announced the discovery of a miwater the canals of the infected districts, and crobe and bacillus, found principally in the thereby cleaned out the poisonous matter and walls of the lower intestines. The French filth which was the direct origin of the devel- Commission was nominally headed by Prof. opment of cholera. Apart from the cholera Pasteur, but was really headed by M. Thuillier, epidemic, there is at present a great deal of who died at Alexandria, a martyr to his scientyphoid fever in the country, and we have just tific zeal. This commission reported that a got over an epidemic of spotted typhus fever.” micro-organism was found in the blood, lo.

While the epidemic lasted, great alarm was cated in the spaces between the blood-globules. felt in Europe, not only among the countries Further experiments are necessary in order to bordering on the Mediterranean, but in Russia, demonstrate the truth of these propositions. which quarantined her Black sea ports, and In the mean time nothing has been discovered later those in the Baltic, and all Europe quar- which in any way modifies the treatment of antined against arrivals of persons and goods previous years. The “ Fyers' treatment," which froin Egypt, in view of the danger of importa- consists in the administration of emetics and tion of cholera. England departed from her purgatives, has again been brought forward. usual conservatism against quarantine, by lay- This treatment, it will be remembered, origiing the responsibility upon customs officers to nated in Mauritius in 1856. make special investigation of the importation A commission was appointed by the German

ease.

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