Page:The National Geographic Magazine Vol 16 1905.djvu/515

circumstances should the surface of the canal be more than 60 feet above the sea, and estimates that at this level the cost would be $178,013,406. A 30-foot level is estimated to cost $194,213,406.

It is recommended that the Chagres River be controlled by a dam at Gamboa, built to a crest height of 200 feet, and the waters of the lake thus created disposed of through tunnels. The work on the foundation of the dam will require from one to one and a half years, and the committee reports should begin at once. The dam at this place, it is stated, involves no formidable obstacles, which is not the case at the Bohio location.

The construction of a dam at Gamboa in this connection would also control the Chagres River, except that it would be necessary to provide a safety spillway by the construction of a tunnel some eight miles in length through the divide, discharging the surplus waters of the Chagres into the headwaters of the Juan Diaz, or the alternative plan of constructing a tunnel four miles long through the divide separating the Chagres Basin from the headwaters of the Gatuncillo, a stream which enters into the Chagres Valley at Gatun. Should this latter course be adopted, it would be necessary to construct an auxiliary channel for the Chagres from Gatun to the sea in order to divert its flood waters into the bay eastward of Colon.

The dam would also provide the water supply for the entire line of the canal, including the cities of Panama and Colon. It would also provide a plant for the generation of electric power sufficient to furnish ample power for the operation of the Panama Railroad and for the operation of any machinery that might be used in the construction of the canal. It would require two years to construct this dam, and, roughly estimated, its cost, including spillways, would be between $15, 000, 000 and $16,000,000, not including the power plant.

Actual work in the Culebra Cut has demonstrated that the entire excavation can be done at a saving of $15,000,000 over former estimates, and is given as a justification for the recommendation for a sea-level canal.

Immediate work is recommended at Colon in constructing a safe harbor. To this end, an outer breakwater is suggested, as well as the construction of an inner harbor at the entrance to the canal. It is recommended that bids be invited for this work.

Other minor features of canal construction recommended include completing the Gatuncillo diversion channel, begun by the old canal company to divert from the canal the Gatuncillo and Mindi rivers and other smaller streams. In connection with this, three small dams must be built—two across the Chagres River near Mindi and one across the Boca Mindi. All of this work is independent of the decision as to a level for the canal, and its immediate execution is recommended. Other subsidiary features depend on the level determined on and are not discussed.

The committee makes these observations in summing up:

"The practicability of certainly and satisfactorily controlling the floods of the Chagres by so simple and economical a method as the Gamboa Lake and its outflow channels, and the reduced cost of excavation as actually demonstrated by the work of the Commission in the Culebra Cut, makes the construction of a sea-level canal at a reasonable cost far more available than has heretofore appeared possible. These recent developments in the conditions attending the construction of the canal are so important as to be almost controlling in character. The remaining element is that of the time required to make the great summit excavation.

"It is to be carefully observed that the results thus far obtained in the Culebra Cut have been reached under disadvantageous conditions of both organization of plant and force. The