123RAGUA CANAL which is then to be dredged, and its outer line protected by an artificial work, which fortunately finds below the shifting river sand a solid clay foundation. This obstacle overcome, the rest of the work offers nothing that modern engineering cannot easily and safely accomplish. Indeed, nature meets man more than half way on the rest of the projected canal line. of the San Juan River, which connects Lake | pleted the work-thus isolating the harbor, Nicaragua with the Caribbean Sea. This harbor, as late as 1858, was an excellent one, with an entrance deep enough to float the largest ships. The San Juan is a large river, averaging about six hundred yards in width, and navigable for light draught steamers during the entire year, while during the rainy season, steamers of four hundred tons can ascend through it to Lake Nicaragua. It empties into the Caribbean Sea through two principal channels, each about twenty miles in length (the Colorado branch and the San Juan proper), and also through a secondary branch leaving the San Juan below its junction with the Colorado, called the Tauro branch. In former years the San Juan River proper carried most of the water, and, while this was the case, its current scoured the harbor of San Juan del Norte, and maintained a depth of twenty-eight to thirty feet at its entrance. From the port of San Juan del Norte the canal line reaches the San Juan River just above where the San Carlos River empties into it from the Costa Rica side. The San Juan, above the mouth of the San Carlos, has no streams of consequence emptying into it. Below the San Carlos, this latter and the Serapaqui River (also emptying into the San Juan from the Costa Rica side) render the main river liable to sudden freshets and unadapted to canal purposes. Above the San Carlos River the San Juan is subject to only such moderate increase of volume as may arise from an increased hight of the level of Lake Nicaragua during the rainy reason. In fact, it becomes a natural drainage channel from the lake, with a fall of only nine inches to the mile. Since 1858, the volume of water going down the San Juan proper has gradually diminished, and has been diverted to the Colorado branch, which now carries seven-eighths of the water from Lake Nicaragua to the sea. The result of this change has been destructive to the har- Where the canal joins the San Juan River, bor of San Juan del Norte. The loss of a scour- just above the mouth of the San Carlos, a pering current has caused a very serious shoaling of manent stone dam, 49 feet high, is to be conthe harbor, and nearly destroyed its entrance. structed, which at once raises the river above The restoration of this harbor is the most diffi- it two feet higher than the present high-water cult problem in the Nicaragua Canal project; level of the lake, and over this dam the San and, while willingly admitting that it can be Juan is allowed to find its way to the Atlanmade a good harbor, I am inclined to the belief tic. There is nothing especial about this dam, that it may cost double the amount allowed for either in hight or length (2,000 feet) to disin the estimates, which is placed at $2,822,630. tinguish it from works of a similar character The plan adopted for this purpose is to turn the elsewhere. The abrupt banks of the river afentire water of the San Juan River down its ford excellent abutments. From San Juan del Colorado branch-a point easy of accomplish-Norte to the dam the canal runs mostly through ment, since nature has already almost com- an alluvial soil, where dredging machinery will shoaled by "silt" deposit to a depth of about twelve feet at low water. Lake Nicaragua is the great feature of this route. Its immense area prevents any floods, as the extreme difference from its low-water level at the end of the dry season and its high-water level at the end of the rainy season is only twelve feet. It furnishes far more water than can ever be used for lockage, while it constitutes an excellent inland harbor, and by its extent and connection with Lake Managua will render subsidiary to the ship canal the territory of the republic, than which there is no richer in natural resources in the world. The Pacific division of this canal is 17% miles long, from the mouth of the Lajas on the lake (before alluded to) to the Pacific seaport of Brito. The elevation above lake level is 42 feet, which, with the lake level above the sea, 107 feet 10 inches, makes the lowest summit at present known between the Atlantic and Pacific oceans, 150 feet. There is nothing special in this cut between the lake and the Pacific. The only obstacle of note is the diversion of the small stream called the Rio Grande, which is a mere brook in the dry season, and never swells to respectable dimensions at any time. This diversion is necessary to prevent the interference of the stream with the canal, which is constructed mostly through a wooded country and solid ground. do most of the work with advantage. The hight | ual current into the river, the lake has been of the lake and river above the dam being then 109 feet 10 inches above sea level, locks (probably seven in number) must be constructed to attain this level. It is proper here to state that, in the matter of locks, the Nicaragua Canal survey requires only what experience has already demonstrated as practicable--a lock having been three years in use on the St. Mary's Canal, constructed by General Weitzel, Engineer United States Army, with a length of 515 feet, and a lift greater than will be needed in Nicaragua. It is in this respect principally that the Nicaragua survey differs from the Panama French survey. The elevation of 109 feet 10 inches in Nicaragua is overcome by locks, while at Panama the De Lesseps survey surmounts an elevation of 294.7 feet by a low-tide, oceanlevel cut. The merits of the two schemes will appear more in detail hereafter. From the San Carlos dam to the lake the river will need a large outlay to fit it for uninterrupted slackwater navigation. Its most abrupt sinuosities must be removed, and its channel cleared of rocks. Above the San Carlos dam are four rapids-the Machuca, the Balas, the Castillo, and the Toro. Of these only the Castillo deserves the name, and I have often run over all of them in river steamers of light draft, while, as before stated, lake steamers, built in the United States, have always reached Lake Nicaragua by passing over them in the rainy season. Of course, the improvement of the river-bed would be made before the completion of the dam, and offers no obstacles that cannot be readily overcome. From the Toro Rapids to the lake (28 miles) the San Juan flows in majestic silencea wide and deep natural canal, needing little expenditure to fit it for heavy navigation. Lake Nicaragua* is a magnificent fresh-water inland sea, with an area of over 3,000 square miles, 10 miles long, and about 35 miles wide, averaging from 9 to 15 fathoms deep, and its surface 107 feet 10 inches above the sea-level, Situated north of it, 17 miles distant and 22.3 feet higher, is Lake Managua, about 30 miles long, which it is intended to connect with Lake Nicaragua by a light draft canal, as subsidiary to the ship canal. The length of interoceanic canal navigation on Lake Nicaragua is 56%1⁄2 miles, from the junction of lake and river to the lake end of the Pacific division of the canal, at the mouth of the little River Lajas; and the only labor necessary thereon is the dredging of the soft mud for about seven miles from the junction of lake and river, where, by the grad * Derived from "Nicarao"-an Indian chief discovered by the Spaniards residing on the shores of the lake-with the addition of the Spanish "agua," or water. At the little port of Brito the Nicaragua Canal enters the Pacific. The harbor is merely a small indentation in the coast line, with good anchorage, but insufficiently protected seaward. Partly by the excavation of the low sandy land at the head of the harbor, and by the construction of a short breakwater from the bluff forming its northern limit, a good harbor can be made sufficient in size to answer every purpose, and as large as many important European ports. Of course, a duplicate system of locks must be constructed in these 171⁄4% miles to overcome the difference between lake and sea level, already stated as being 107 feet 10 inches. The original United States survey was made for ten locks, each of 104 feet lift, but it is now proposed to increase the lift and diminish the number of locks to seven, which will save expense and economize time. It will be noticed that the work I have described is not only an interoceanic canal, but forms a system of internal improvement which will insure a rapid development of the republic of Nicaragua, and thereby materially add to the revenues of the canal company. On the various advantages justly claimed for this route-climatic, engineering, commercial, and meteorological—it is foreign to the purpose | by thirteen culverts, which carry them under of this paper to comment, and I close this description of the Nicaragua Canal route with the following figures, which the reader should refer to hereafter for comparison: Total length of interoceanic navigation, 173.57 miles. Canal, from San Juan del Norte to San Carlos dam, 35.90 miles. Slack-water river navigation, from San Carlos dam to lake junction, 63.90 miles. the canal, to resume their channels on the other side of it. Besides the provision made for the thirteen small streams, there are in this section three minor branches, turned into side drains. An examination of the map will show that this section of the work runs nearly parallel with a range of hills inland, from which these streams start. Disposing of these minor obstacles, and raising the canal level by twelve Lake navigation, from lake junction to lake end of locks, at convenient intervals, the work apPacific division of canal, 56.50 miles. Extreme summit level, between Pacific and Atlantic oceans, 150 feet. Total length of canal to be constructed, 53.15 miles. Engineer's estimate of time for construction, 5 years. THE PANAMA CANAL ROUTE. There have been two surveys made at the Panama Isthmus for an interoceanic canal: First, a United States Government survey, under the superintendence of Captain E. P. Lull and Civil Engineer Menocal, both ranking at the head of their profession in the United States navy, and forming, with other officers and men of the naval service, about the same party which had previously made the Government survey in Nicaragua; second, the survey lately made by French engineers, under the control of Count❘ de Lesseps. The United States survey is for a lock canal, with an elevation of one hundred and twenty-four feet, and the French survey for a low-tide level canal, without locks, through a summit level of two hundred and ninety-five feet above its surface. The Panama Railroad is forty-seven and a half miles long, and both surveys follow its track approximately. I will first describe the American lock canal project. | Leaving the Atlantic at Aspinwall about one mile inside the present railroad wharf, the canal enters a low, swampy region, densely covered with tropical vegetation. Through this region and to the river Chagres there are two engineering difficulties to be contended with: First, the maintenance of the banks of the canal through a soil of such consistency, especially during the rainy season,* that it may fill in as fast as dredged, which difficulty could, if necessary, be overcome by training walls; second, between the Atlantic and the Chagres River there are thirteen streams running across the canal line, of small dimensions during the dry season, but troublesome when swollen by heavy rains. The American survey provides for these *At Aspinwall, during the year 1872, the enormous precipitation of 170.18 inches was registered. proaches the key of the Panama Canal survey, -the River Chagres. Where the canal crosses the Chagres, near the present railroad bridge, it has a channel nineteen hundred feet widefrequently insufficient to carry its waters, which, only a year since, inundated the valley, swept the iron bridge down the river, and covered the railroad track for days. In fact, the Chagres is a violent, rapid stream during the rainy seasons, and has been known to rise forty-eight feet in one night. Over the Chagres, on a viaduct built on twelve arches, the canal is carried, leaving the river to find its way unvexed to the sea. This work, practical and permanent, although necessarily expensive, solves the problem of the Panama Canal. A feeder, for locking purposes, is run from the Chagres, tapping it twelve miles up the river, and there appears no doubt of the capacity of the river to furnish all the necessary lockage water, although it might tax it seriously, with a large traffic, during the dry season. Past the Chagres, the character of the work in not formidable, although, owing to the high summit, the excavation through the Culebra division is very heavy, even with the reduction made by the elevation of the canal, which, again seeking sea-level by thirteen locks, finally finds the Pacific quarter of a mile east of the present railroad wharf; whence, owing to the large rise and fall of tide, it is carried about two miles out into the bay until it meets deep water. The survey for the Panama Canal above described is considered by the best engineering talent in this country as the only manner in which the difficulties of the project can be surmounted at any cost within commercial limits. Count de Lesseps has decided that he must have a low-tide level canal across the Panama Isthmus, and, while he may over-value its advantages, his opponents must concede their existence. The French survey leaves the Atlantic at Navy Bay at the same place as the United States survey-in fact, both surveys follow the railroad approximately, and both encounter the same obstacles, but surmount them differently. Both surveys include a breakwater in Navy Bay (Aspinwall), protecting the end of the canal from the northers experienced there at times, also making a safe anchorage near the entrance. Of course, a depth of twenty-eight feet below low-tide level involves vastly increased excavation, and the streams before described as crossing the canal line before it reaches the Chagres are taken care of by a lateral canal, also used to carry the surplus waters of the Chagres, as will be hereafter described. On reaching the Chagres, De Lesseps attempts the stupendous task of entirely obliterating that river before it reaches the canal, the surface of which crosses the river-bed forty-two feet below its bottom. At Gamboa, about two miles above the canal line, an enormous dam is constructed across the whole valley of the Chagres, creating a large artificial lake, which is to hold the entire volume of the river, the waters of which are gradually to be drawn off by the lateral canal before alluded to, and, to a limited extent, into the canal itself. To judge of the character of this work, the following estimate from the French survey is given herewith: Length of dam, feet.. Hight above bed of the Chagres, feet. Hight above canal level, feet.. Hight above canal bottom, feet.. 5,000 130 172 199 Estimated cost, 10 per cent. contingency..$20,000,000. It will be noted that the bottom of the canal passes in front of the dam, seventy feet below the river bed, and that the Chagres River is wiped out of existence between the canal and the Atlantic. When the enormous rain-fall, the violent freshets, and the large amount of sediment and floatage brought down by floods are considered, one begins to realize the enormous difficulties of the project, the doubtful results of the attempt, and the impossibility of estimating additional cost which may be caused by contingencies liable to occur. Presuming its completion, will this dam not be a standing menace to the canal, passing in modest silence two hundred feet below its top? What will be the result of a moderate earthquake shock, or of seepage during the rainy season? Thus ob | literating the Chagres, the canal passes on into the Culebra division, cutting through an elevation a few inches less than three hundred feet, of course with an immensely increased excavation as compared with the United States survey, but encountering otherwise no formidable engineering obstacles, and finally reaching the Pacific through the valley of the little Rio Grande, about six miles west of the city of Panama, and there meeting deep water about four miles outside the high-water mark. The mean sea level of both oceans is now known to be the same, but while at Aspinwall the tide ebbs and flows from one and a half to two feet, at Panama the tidal movement is eighteen to twenty-six feet. The American, as well as the French survey, overcome the difficulty by placing a tidal lock at the Pacific end of the canal, which completely controls the question. Such is the French survey for a sea-level Panama canal. The attention of the reader is called to the following comparative figures: Isthmus will give him many grades and curves. He at first estimated the cost of such a railway at half the cost of a ship canal, but his present idea is that it will cost $75,000,000, which at once detracts from his scheme the principal merit heretofore claimed for it, which was comparatively small cost, for there is every pros ed for a like amount; and while the depreciation, and wear and tear of his railway, subjected to the action of a tropical climate, will necessarily be great, a ship canal improves with age-considerations of no little importance. navigation, making a total of 172 miles, and former surveys for railway and canal purposes have found the lowest practicable summit at 754 feet. The canal project for this route was abandoned because of the high summit necessitating a large number of locks, with a scant water supply, while a tide-level canal is impossible at any admissible cost. For a ship rail-pect that the Nicaragua Canal can be constuctway it offers advantages over any American isthmus, and an ordinary railway is now being constructed there by an American company. The Coatzacoalcos River is a stream of respectable magnitude, running northerly across the northern slope of the isthmus, with 12 to 13 feet of water on its bar, which it is proposed to deepen sufficiently to admit the largest ships, which can ascend the river about 25 mileshow far before arriving at the Atlantic end of the proposed railway, I presume Mr. Eads himself has not decided. There are no formidable obstacles in the way of building an ordinary railroad across the isthmus beyond the heavy cuts and fills usually found in a country of that character, and the railroad finds its Pacific terminus at Salina Cruz, near Ventosa, at the head of the Gulf of Tehuantepec, where a port must be constructed. Probably Captain Eads can improve the Coatzacoalcos River for heavy navigation 25 to 28 miles, and his railroad will be about 123 miles long. He estimates the cost at $75,000,000. It has been my purpose to avoid a discussion of the merits of the three routes here described, but it will be impossible to do so in the case of this project, if the reader is to acquire an intelligent idea of it. My high respect for the ability of Captain Eads, my esteem for him, founded on a slight personal acquaintance, and the fact that I can lay claim to no technical knowledge of civil engineering, are good reasons for approaching this subject with deference, and I must regard myself as merely a student of the project. Captain Eads takes the ship out of water by a submerged inclined track, on which the cradle is run deep enough to allow the ship to be placed upon it, properly lined and blocked, after which a stationary engine hauls cradle and ship out of water to the railroad proper, where four "Mogul" locomotives are placed ahead of it on a twelve-rail track, which haul ship and cradle to the other end of the track, where, by a reverse process, the ship is again placed in the water. Of course, there must be a cradle in use for each ship being transported simultaneously. The grades are overcome by tipping tables and the curves by turn-tables, as can readily be imagined, of gigantic size. How many of these he will need cannot be known until surveys are completed, but I fear the Tehuantepec That Captain Eads can construct a ship railway across Tehuantepec, there is little doubt; that he can so construct it as to meet all the requirements of the case, is another consideration. His mechanical appliances for overcoming the objections I was able to point out to him appeared complicated, while the engineering obstacles of curves, grades, etc., his intimate knowledge of his profession had already indicated methods placing them under his control. He was willing to handle a loaded ship as carefully as I demanded, while it was my object not to allow previous prejudices to affect my judgment of the merits of the scheme. In one respect, however, I fear he has underrated the difficulty of his project. I doubt if at Tehuantec, or on any tropical American isthmus, he can find a foundation for such a road as he wishes to build. The "cuts" may support it, but the "fills" may fail to do so. The success of the scheme depends on extreme rigidity of road and cradle, and if in tropical countries foundations are always troubling railroad engineers under ordinary tracks, what are we to expect under a weight of fifteen or twenty thousand tons concentrated within the limits of the cradle carrying the loaded ship? Captain Eads is one of the greatest living engineers, and, if capitalists will furnish funds, he may build his railway; but unless it is cheaper than a canal what advantage does it offer? Why try an experiment when a certainty offers the same results? However, in the absence of a survey with instruments of precision, it is probably unfair to discuss the project at all, and I dismiss it, with great respect for the ability and resources of the illustrious projector. COMMERCIAL RESULTS ANTICIPATED. That an American interoceanic canal will effect great changes in the world's commerce none can doubt, but what little I shall have to say on this branch of the subject will refer to the effect it will have upon American commercial interests generally, and especially upon |