Page:Popular Science Monthly Volume 16.djvu/403

Rh which they were no longer accustomed? What would then become of the insurance which had been arranged for the expected passage through a canal which was no longer of any use?

If, in speaking of Tehuantepec, which line, however, is no longer thought of for a canal, I have somewhat enlarged on the inconveniences which would arise from earthquakes, it is because they also appear to me to apply to the canal by Nicaragua, and to put it out of consideration, even were there no other reasons.

Let us look, all the same, at other contingencies which are noticeable at Nicaragua.

It would be a long and difficult task to actually begin the work, because, before the great dockyards of the canal could be built, it would be necessary to make a harbor at Grey town, the success of which does not appear to be assured, and which at any rate would be very expensive.

Starting at this harbor, the canal, when leaving the San Juan River, would for several kilometres be suspended over the valley by immense dikes holding continuously a weight of water 8·50 metres high. There the slightest leak would become a breach, any breach a serious rupture, and any rupture a complete disaster. At what possible expense could the absolute security of these great dikes be assured?

To continue: we enter the San Juan River, kept in bounds by a large dam, which, however, is not enough to assure everywhere sufficient depth of water in the shallowest parts; where there is not depth enough it would be necessary to blow up or excavate by dredges a channel one hundred metres wide by eight and a half metres deep. To make this channel would be difficult, to maintain it against what would constantly come in to fill it up might be still more so.

Let us go on until we reach the lake; here comes another difficulty. At the place where the San Juan leaves it, other torrents bring sand into it, and also mud to a considerable extent. A new bar would have to be dredged, but probably only for a time; a channel would have to be kept open in an immense sliding sand-bank by very long and costly dikes, an objection which does not seem to have been provided for in any of the plans offered.

The passage of the lake seems easy; the cut to be made to reach the Pacific offers no remarkable difficulties; but this descent, on account of its short length, can only be done by locks close together, and locks so arranged offer for a quick movement of vessels serious objections, and necessitate a considerable loss of time.

Without dwelling too much on this subject, let us be content to take as an example the Caledonian Canal. In visiting it some years ago, as an engineer and a tourist, I was struck at seeing that, to avoid passing through it, a reshipment was considered preferable. I have said enough to show my reasons for refusing to accept the Nicaragua plan.

Next comes the project by Panama with locks. Here, as if