TRANS-ISTHMIAN CANAL. ■ire TRANS-ISTHMIAN CANAL. two principal routes, the Nicaragua and the Panama, though there also has been a discussion of a number of secondary routes the principal of which are the Tehuantepec, the San Bias, and the Caledonia Bay. All of these routes have been investigated by engineers and some of them have received continued study for many years. The most thorough and comprehensive study of re- cent years was that made by the Isthmian Canal Commission in 1899-1900, and not only were the two main routes discussed but also other possible projects as mentioned below. The political ques- tions involved have largely been confined to the Nicaragua and Panama schemes and as these propositions have attracted such widespread at- tention in the past and as each possesses certain unique features botli engineering and otherwise, they will be found treated under their respective heads (see Nicaragua Canal and Panama Canal) , while below will be given a summary of the features of other proposed routes. Tehuantepec Route. The well-known geo- graphic conditions at Tehuantepec and between the Nicaragua and Panama Canal routes made it unnecessary to explore those parts of the Ameri- can isthmus for other possible locations for an interoceanic canal, and the commission mentioned limited its investigations to what is generally known as the Darien country, extending from Panama to the Atrato River. For about 80 miles the width of the isthmus in this region does not exceed 40 miles, except at one or two headlands which project beyond the general line of the coast. The narrowest point is at San Bias, where the distance from Mandinga Harbor to the shore of Panama Bay is only 31 miles, two miles less than from the head of the bay at Limon, at Colon, to the mouth of the Ber- nadino. On the eastern side of Panama Bay, about 100 miles from Panama, an estuarj' known as San Migviel Bay extends into the interior to within 33 miles of Caledonia Bay, on the Atlantic side. This bay of San iliguel, -on the Pacific, and San Bias and Caledonia bays, on the Atlantic side, afford excellent harbors and canal ap- proaches. Between Panama and San Bias the ridge of the Cordilleras crosses from the Pacific to the Atlantic side and continues there to the mouth of the Atrato River. As the existence of practicable and feasible routes in this section depended upon the height and continuity of the divide, its crest was ex- amined all along the line, with as much care and accuracy as was practicable under the conditions which existed, for the discovery of gaps and de- pressions, so as to ascertain whether any were sufficiently low for canal purposes, and measure- ments were made of those which promised the most favorable results. The ridge was traced continuously on the ground from the head of the river Carti, a little east of Mandinga Harbor, in San Bias Bay, to the head waters of the Chagres, and thence down the river to the Panama Railroad a total distance of 241/2 miles; also near Caledonia Bay from the Carreto summit, to the Sassardi summit, a dis- tance of 27 lo miles. The lowest elevation in the former section was 956 feet, in the latter 683 feet. Between these two sections from San Bias Bay to Caledonia Bay, a distance of 81 miles in an air line, and from Caledonia Bay southward to the Atrato River, the examination was made from the sea, and the elevations of the higher peaks, as well as the gaps and their distances were determined. The result showed that there was no probability of any suitable depression within these limits. In addition to these investigations, a survey was made from San Miguel Bay, on the Pacific side, up the Chucunaque and Chucurti (Sucubti) rivers, which was almost though not quite con- nected with the work done near Caledonia Bay. After the results of the general exploration were determined, the examination of other possible routes was limited to those sections where the isthmus was narrowest, where the coast lines of- fered good harbors, and the indications along the divide were the most promising. These condi- tions were found near San Bias Bay and Cale- donia Bay. East of San Miguel Bay the isthmus widens, and no route can be expected there less than a hundred miles in length. San Blas Route. The San Bias route extends from the bay of that name to the mouth of the Bayano, on the Pacific; it has been advocated as the shortest line between the two oceans, which is true. The most complete plan developed in- volves a tunnel at least seven miles long. While not necessarily impracticable, such a tunnel would be very objectionable and would render the line inferior either to the Panama or the Nica- ragua location. Caledonia Bat Route. The distance from Caledonia Bay to tide water on the Savana River is about 30 miles in a straight line. Studies have been made of three lines across the divide, all of them striking the same point on the Savana River, near the mouth of the Lara, the approach on the Atlantic side being through the three val- leys of the Caledonia, the Aglaseniqua, and the Sassardi. The distance from Caledonia Bay to the mouth of the Lara varies from 32 miles by the Sassardi route to 36 by the Caledonia route. The Sassardi route has not, however, been ex- plored through its whole length, and it is pos- sible that an actual survey would make it as long as the Caledonia route. Each line would require a tunnel. If the Sassardi route were taken, the length of this timnel, assuming an open cut to be used to the depth of 400 feet, would be about 1.6 miles. On either of the other two the tunnel would be about two miles longer, while the approaches on the south side w'ould be much heavier. These surveys indicate that the Sassardi route is probably the best of the three for a sea-level canal. The indication cannot be regarded as con- clusive, because a thorough survey and develop- ment of the sub-surface material might show in- superable difficulties, which would be more likely to exist in the tunnel than elsewhere. The cost of a canal upon this line would be excessive and the tunnel more objectionable to navigation than the locks on the other routes. Caledonia Bay is virtually tideless. San Miguel Bay has a tidal range of 20 feet or more. This heavy tide causes currents in the Savana River of sufficient force to be a seriovis menace to navigation, and it would be necessary to build a tide lock near the mouth of the Savana. The distance from the mouth of the Lara to the tide- lock site is about 14 miles, the upper portion of which is in a narrow river which would require enlargement for a canal. This makes the total
