The expense of the Nicaraguan Canal was estimated by Napoleon at only four millions sterling; but it is obvious, from the Prince’s own statements, that such a passage as he contemplated would only have afforded draught of water for vessels of 300 tons. Napoleon’s object was, however, quite as much to promote emigration, trade, and civilisation in the State of Nicaragua, as to open a communication between the two oceans.[205]
The river San Juan de Nicaragua directly connects the Atlantic with the south end of the lake of the above name, from the northern end of which but a few miles intervene to the Pacific. Various surveys have been made of the river, with a view to the construction of a canal. In 1837-8 Lieutenant Baily[206] was employed by the Central American Government to explore the route. He found that the surface of the lake of Nicaragua is 121 feet 9 inches above low water in the Atlantic. The river San Juan, in its course of 79 miles from the lake, varies in depth from 9 feet to 20 feet, and its course is broken by various rapids, some of which are of considerable length. The summit-level of the mountain chain which divides the valley of the lake from the Pacific is 487 feet above the lake, and a tunnel of nearly 16 miles long would have to be pierced through this wall in order to reach the port of San Juan del Sur on the Pacific. The total length of navigation, through river, lake, and canal, according to Mr. Baily’s plans, would be 190 miles.
The port of San Juan del Sur is narrow at the entrance, but widens within the harbour. It is surrounded by high land, except from W.S.W. to W. by S. The depth of water at the entrance is 3 fathoms, and the width 1100 yards. Ships could thence go up for a mile and a half, but the amount of excavation required for a canal 30 feet deep and 50 feet wide was estimated at not less than 162 million cubic yards, which has been stated to be more than that required for the construction of 2000 miles of English railway—a figure quite conclusive against this scheme.
In 1852 the route was surveyed by Colonel Childs,[207] who proposed to descend from the lake by fourteen locks to Brito, on the Pacific, where, however, there was no harbour. The length of this route was given as 194 miles.
To avoid the difficulty of cutting through the ridge, it has been proposed to continue the navigation from the extreme north of the Lake of Nicaragua, by the Estero de Panaloya and the river Tipitapa to the Lake Leon, or Managua, and thence to the port of Realejo, on the Pacific, or, yet more to the north, to the Estero Real, an arm of the Gulf of Fonseca. But it has been pointed out that the length of the navigation would thus be increased by a hundred miles, and it is doubtful whether Lake Leon could furnish the water necessary for lockage, in both directions, which it would have to supply.
The Nicaragua route, therefore, whatever may be its advantages, if any, over that of Panama, is liable to the objections of great length, large works, numerous locks, and the no less formidable danger, to use the words of Humboldt, that “there is no part of the globe so full of volcanoes as this part of America, from the 11th to the 13th degrees of latitude.”[208]
The distance from ocean to ocean by the route that has recently received the approval of the United States Government, and is now in course of apparent realisation, is 169·8 miles. Of actual canal there will be 40·3 miles, the remaining 129·5 miles being free navigation through Lake Nicaragua, the Rio San Juan, and the valley of the Rio San Francisco.
Beginning on the Pacific side, the canal starts from the port of Brito, situated about 12 miles north-west of San Juan del Sur, the Pacific terminus of the famous gold-fever transit route, where there is a broad channel, 342 feet wide at high water, reaching inland about 1½ miles to the tidal lock. This lock lifts the canal 24·2 feet above high tide of the Pacific.
From this lock, which is really the beginning of the canal—the portion between the lock and Brito being in reality an extension of the harbour—the canal ascends the broad gently-sloping lower valley of the Rio Grande, which is to be diverted into the lake by an artificial channel, rising by means of three or more locks of from 26 feet to 29 feet lift, till, at a point 8¾ miles from Brito, it reaches the western end of the summit level, 110 feet above mean tide; thence it proceeds through the upper valley of the Rio Grande and across a moderately rolling country to the summit or “divide,” between the Pacific and the lake, 41·4 feet above the level of the water in the canal; then through the valley of the Guscoyol, a tributary of the Lajas, and along the bed of the diverted Lajas to the lake, a total distance of 8½ miles from the last lock and 17·27 miles from Brito.
Between the lake and Brito one small stream is taken into the canal by a receiving weir. The river Tola and several small streams coming from the north are to be passed under the canal, and along its lower portion there will be ditches to intercept the surface drainage, which is inconsiderable, and convey it to the sea.