Journal of the

Western Society of Engineers.

The Society, as a body, is not responsible for the statements and opinions advocated in its publications.

The great range of mountains which stretches almost continuously from the Arctic Ocean to the Straits of Magellan and separates the Atlantic and Pacific slopes of the continent has two depressions where canal routes are apparently practicable. One of these is where the American Isthmus is crossed by the Panama Railroad. The projected Panama Canal is located through it, and construction is considerably advanced. The second is in Nicaragua. No other practicable route for a canal crossing is known to exist through that extended mountain range. Of the two routes, the northern one across Nicaragua is the one which offers the most advantages to the interests of the United States, because it would be the shorter one between our Atlantic and Pacific coasts or between either of them and the countries opposite the other. It has been the subject of our diplomacy for nearly a century, and for nearly half that time has been frequently visited and explored by our engineers. At the present time a survey more extended and thorough than has been undertaken heretofore is in progress, under the direction of a United States commission.

Of even more direct interest to this society is the inspection of the route now being made by a party of leading American contractors, under the guidance of one of our most distinguished members. It seems, therefore, a fitting time to present here an outline of the engineering features of the project. It will conduce to a better understanding of the subject if notice be first taken of the general features of the region traversed by the

route.

The key to the Nicaragua route is Lake Nicaragua. This magnificent body of fresh water has a length of about 110 miles,

lying in a northwest-southeast direction, nearly parallel with the Pacific Coast and at a minimum distance therefrom of 12 miles. Its maximum width is about 45 miles and its area about 2,700 square miles. These figures are only approximate; the region has never been carefully surveyed, and no two maps agree.

The elevation of Lake Nicaragua above mean tide is only about 102 feet at ordinary low water, and it rises in ordinary seasons about 8 feet, making ordinary high water 110. Its outlet is near the southeast end, where its waters discharge into the San Juan River and thence to the Caribbean. This lake would constitute a vast reservoir for the supply of the summit level of the proposed canal.

Northwest of Lake Nicaragua and about 25 miles distant is Lake Managua, with a length of 35 miles and breadth of 20. Its surface is about 25 feet above Lake Nicaragua, into which it drains intermittently.

About 30 miles north of Lake Managua the great continental mountain range forks. One branch passes east of the lakes and terminates on the left bank of the San Juan, about 25 miles from the Caribbean. It has a height generally of 2,000 feet and upward, and opposite the northern portion of Lake Nicaragua it has a bold, rocky outline; farther south the outlines soften, and a few miles from its terminus on the San Juan there is a low pass, through which the canal line has been located, as will appear later. The pass is known in canal literature as the "East Divide." The second branch of the continental mountain range passes west of the lakes. It is much broken. Near the head of Lake Managua it is much depressed, while on the west side of Lake Nicaragua, opposite the middle of the lake, it is almost imperceptible for a short distance, and the canal line crosses it at an elevation of only 154 feet above mean tide, or 44 feet above ordinary high water in the lake. This range is generally less bold than the one east of the lake, but it contains several volcanoes, which tower so high above the main range that they appear isolated. This range is the true continental divide; the point where it is crossed by the canal line is the lowest summit point between the Arctic and Antarctic oceans. It rises sharply south of the canal, passing into a lofty range which trends easterly in Costa Rica and forms the southern boundary of the drainage basin of Lake Nicaragua and the San Juan River. The basin of the lakes is, roughly, a rectangle, with its run much depressed in places on the western side and quite broken away in the southeast corner, at its outlet. The area of the basin is about 12,000 square miles, of which 3.300 drain into Lake Managua, the remainder directly into Lake Nicaragua-lake areas included in both cases.

The San Juan River, the lake outlet, is about 120 miles long and has a basin of about 4,000 square miles, excluding the area draining into the lakes. It has, therefore, a considerable basin of its own. In its upper course it is obstructed by several rapids. All but one are navigable by light-draught steamboats except at

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its own. In its upper course it is obstructed by several rapids. All but one are navigable by light-draught steamboats except at

low water. On the north side of the river the range separating its basin from the next one to the north is only 15 to 20 miles distant, according to the maps. The slopes are steep, and the rainfall finds its way quickly to the main river through a large number of small streams. The loftier mountain range on the south side of the river is about 50 miles distant and the streams are larger. In the river valley near the lake there are occasional swamps, but the country is generally hilly; the hills become bolder farther down and at short intervals steep spurs abut against the river, which is therefore crooked. Except in the swamps the soil is a firm clay and the river banks are stable, this characteristic continuing to within a few miles of the sea coast. For the upper half of its course the river receives little sediment, and its bed, like its banks, is stable. About sixty-five miles from the lake it receives a large tributary, the San Carlos, which drains the slopes of some great volcanoes in the lofty mountain range in Costa Rica. In times past these volcanoes have thrown out vast quantities of sand, which the streams have gradually carried off. The San Carlos has transported it to the San Juan and filled the bed of the main river, below the junction, with shifting sand to an unknown depth. The banks, however, remain stable, except near the sea coast, where the river for a few miles passes through a region built up of sand of probably similar origin.

A few miles below the mouth of the San Carlos swamps again appear, particularly on the south side, where they are of great extent. On the north side of the river, between the mouth of the San Carlos and the pass in the eastern mountain range already referred to as the East Divide, are several small streams whose valleys are approximately parallel to the main river, and separated from it by ranges of hills of moderate elevation, through which they finally break to join the main stream. This peculiar topography has been taken advantage of in locating the present canal line.

Between the East Divide range and the coast of the Caribbean the country is flat and swampy and intersected by a network of inter-communicating streams.

The Caribbean, like the Gulf of Mexico, is essentially an enclosed sea, and the tidal range along the Central American coast is about one foot. On the Pacific side it varies greatly with the configuration of the coast, the ordinary range being about eight feet on the coast of Nicaragua.

The western coast of the Caribbean is in the trade wind region, and the rainfall is much greater than any we are accustomed to, being in general about 150 inches per year, but at Greytown, the Atlantic terminus of the Nicaragua route, it is nearly double that amount and is the greatest of record on the continent; on the west side of the lake the average annual rainfall is only 65 inches per year. Heavy down-pours are common over the entire route, the records showing 3" in one hour, 9" in 24 hours and