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Pedro Miguel, the level is lower than at Obispo, 8 miles back.
The Continental Divide covers a distance of 9 miles from Bas Obispo through Empire and Culebra to Pedro Miguel, and of this the deepest part is 6 miles in length, from Las Cascades to a point near Pedro Miguel, and forms the heaviest part of the so-called Culebra Cut. From Pedro Miguel to Miraflores, a distance of 11 miles, the land continues to fall, and the canal fortunately finds the low valley of the Rio Grande as an available path to the Pacific. This valley from Miraflores to the sea is very little above the sea level, and beyond the lowlands is lined on both sides with much higher ground and hills, of which Sosa Hill and Ancon Hill are the best-known. The distance from Colon to Miraflores is about 394 miles, and from Miraflores to the Pacific is 57 miles, or a total of about 45 miles from Colon to the shores of the Pacific.
The waters of Panama Bay vary in depth from 7 to 32 feet, and the bottom slopes off into the deeper waters of the Gulf of Panama and the Pacific Ocean. (See plan No. 3.) About 24 miles off shore from the mouth of the Rio Grande is a group of islands with both lowlands and mounds. The question as to whether the canal should pass to the east or to the west of them was decided one way by the French and the opposite way by the Americans, the reasons for which will develop later.
Having thus observed the principal natural features of the canal route, we may note to what extent the topography was affected by the French operations, pay
ing but little attention to the period from 1889 to 1904, for the New Panama Canal Company, aside from its comprehensive preparatory technical work, wisely did only enough excavation to hold the charter.
As already noted, the French canal was excavated from Colon through the lowlands on the easterly shore of Limon Bay, and as far as Gatun it was later used by the Americans for carrying materials to the locks. It was partly excavated as far as Bohio, a total distance of about 17 miles.
The bottom width of the canal was not over 72 feet, and the depth of water averaged about 20 feet for half the length, and over the part toward Bohio, where the ground was higher, did not go below sea level. The canal crossed the Chagres River at several points, and the river water flowed freely into the canal. At Gatun, where the canal on its way to Colon leaves the river bed, about one-third of the flow continued through the canal. The large bend in the river where it sweeps toward Gatun is “short-circuited” by a cut-off known as the Chagres diversion. Deadening this bend eliminated two river crossings and shortened thg distance to the mouth of the river. A part of this diversion is utilized in the spillway channel of the completed canal. There were also a number of other such diversions. At Bohio considerable rock excavation was done after the sea-level canal was given up in favor of a lock canal. From Bohio to Bas Obispo the canal excavation cut the course of the Chagres a great many times. Across the Continental Divide the French cut a comparatively narrow trench, which at its deepest point was 165 feet below the original surface, and left about 190 feet more of cut to accomplish a sea-level canal, and over 100 feet for the French lock canal. On the Pacific end a partial channel was dredged, and also the necessary diversions on each side, which captured the water from the river branches and discharged it into the bay before it could reach the canal. A total amount of 80,000,000 cubic yards of excavation was done all along the canal. Some of it was deposited on the line of the much wider canal finally adopted by the Americans, and required re-excavating; some of the channels were partially filled by silting. Besides excavation, the French left behind them some 2000 buildings and a vast amount of equipment. Much of it was overgrown with a dense jungle during the 15 years of inactivity, and was lost until years after.
THE CHOICE OF TYPE
With this brief excursion across the Isthmus, observing the various natural and artificial features of importance, and which an examination of the maps will aid in fixing in the mind, we are in a better position to consider the problems that confronted the United States when it was necessary to decide on the type of canal. The choice lay between a sea-level and a lock canal. The United States was determined to have the best canal, regardless of cost or trouble. The French ideal was a sea-level canal which they epitomized as the “Straits of Panama.” But their resources would not allow them to attain their ideal, so they adopted a lock canal as a makeshift and temporary expedient. Knowing this, the American tendency was to regard the sea-level canal as something more difficult to attain and, therefore, as something more valuable and more desirable. Furthermore, the average citizen or average official is unfamiliar with locks, and these devices convey to him an idea of something vague and hazardous. These feelings had first to be overcome before the nation was ready to consider the question on its true merits. In view of this, and of the vital necessity to the success of the enterprise of deciding the question of the type of canal correctly, the President appointed an International Board of Consulting Engineers to advise in the decision as to type and probable cost. The board was presided over by a retired major-general of the United States Army, and included in the membership seven American and five foreign engineers, all most eminent in their profession and experienced in the problems involved in the construction of the canal.
The divided report of the board was unexpected and in a way disappointing. Five of the American engineers favored the lock type, but they were in the minority, as the chairman, the two remaining American engineers and all the five foreign engineers voted for the sea-level canal. Five members of the Isthmian Canal Commission and the chief engineer approved and recommended the lock canal, while the other member favored the sea-level type. On a poll of individuals of both bodies, nine were for the sea-level and eleven for the lock canal. It remained for the Secretary of War and the President to consider, with the various reports of facts and state