APPENDIX E.


 HYDRAULICS OF THE PANAMA CANAL.
 By HENRY L. ABBOT.


 (a) SOME OF THE HYDRAULIC PROBLEMS OF A SEA-LEVEL PANAMA CANAL.
 Granting for the sake of the argument that by a dam at Gamboa, and deep cuts or tunnels to the Pacific or Atlantic, the upper Chagres River may be diverted from the canal route, although neither of these assumptions is warranted by known technical data demonstrating that the increased cost and increased time of construction would be justified, there still remain other hydraulic problems well worthy of study. These pertain to the topography of the cafial route, and to the volumes contributed by streams entering below Gamboa.

 TOPOGRAPHY OF THE CANAL ROUTE.

 Starting from Colon the route, after traversing a swamp to kilometer 4, follows the valley of the Mindi to kilometer 6.5, and then enters the valley of the Chagres, the lowest level of which it occupies as far as Obispo, at kilometer 45. At the low stage of the river the level of the Gulf extends to Bohio, at kilometer 23.5, and all tributaries below that point would enter the canal route at levels not differing materially from that of the Gulf. At Bohio begins the anticlinal geologic arch of the Isthmus which, attaining its maximum height at the Culebra, sinks to sea level near Miraflores. Throughout this entire distance of 23 miles all streams cut by the canal would naturally enter it in the form of cascades. These streams from Bohio to Obispo are properly classified as direct tributaries of the Chagres. From Obispo the route follows to the divide at the Culebra the valley of an important tributary concerning which some confusion in name exists. The early maps designated the main stream throughout as the Obispo, but those of later date extend the name of one of its upper branches, the Camacho, from its original junction opposite kilometer 51.3 to kilometer 47, where the name Obispo is resumed. There are thus now two disconnected Obispo rivers, the upper and the lower, the confusion of name resulting from necessary artificial diversions at points where affluents entered the excavation. After passing the continental divide at the Culebra, the route follows down the valley of the Rio Grande to tide water near Miraflores, and in this section the reduced rainfall simplifies the problem.
 For a proper understanding of this hydraulic problem it is desirable to know the number of tributary streams cut by the canal, and the heights of the cascades which would naturally result. This information will be found in the table following for the more important affluents, many of the smaller class being omitted.
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