THE PANAMA ROUTE FOB A SHIP CANAL. 267 



of the Chagres, therefore, instead of constituting the obstacle to con- 

 struction and convenient maintenance of the canal heretofore sup- 

 posed are deprived of all their prejudicial effects and transformed into 

 beneficial agents for the operation of the waterway. 



The highest floods are of short duration, and it can be stated as a 

 general law that the higher the flood the shorter its duration. The 

 great floods which it is necessary to consider in connection with the 

 maintenance and operation of this canal would last but a comparatively 

 lew hours only. The great flood flow of 140,000 cu. ft. per second 

 would increase the current in the narrowest part of the canal below 

 Obispo to possibly 5 ft. per second for a few hours only, but that is the 

 only inconvenience which would result from such a flood discharge. 

 That velocity could be reduced by additional excavation. 



Inasmuch as this system of control, devised and adopted by the 

 Isthmian Canal Commission, is completely effective in regulating the 

 Chagres floods, the reservoir proposed to be constructed, by the new 

 Panama Canal Company at Alhajuela on the Chagres about twelve 

 miles above Obispo, is not required, and the cost of its construction 

 would be avoided. It could, however, as a project be held in reserve. 

 If the traffic of the canal should increase to such an extent that more 

 water would be needed for feeding the summit level the dam could be 

 built at Alhajuela so as to impound enough additional water to accom- 

 modate, with that stored in Lake Bohio, at least five times the 10,000,- 

 000 annual traffic already considered. Its existence would at the 

 same time act with substantial effect in controlling the Chagres floods 

 and relieve the Gigante Spillway of a corresponding amount of duty. 



The locks on the Panama route are designed to have the same dimen- 

 sions as those in Nicaragua, as was stated in the lecture on that route. 

 The usable length is 710 ft. and the clear width 81 ft. They would 

 be built chiefly of concrete masonry while the gates would be of steel, 

 and of the mitre type. 



The great dam at Bohio raises the water surface in the canal from 

 sea-level in the Atlantic maritime section to an ordinary maximum of 

 90 ft. above sea-level ; in other words, the maximum ordinary total lift 

 would be 90 ft. This total lift is divided into parts of 15 ft. each. 

 There is therefore a flight of two locks at Bohio, indeed there are two 

 flights side by side as the twin arrangement is designed to be used at all 

 lock sites on both routes. The general dimensions and the arrange- 

 ments of these locks with the requisite culverts and other features are 

 shown in the acompanying plans and sections. They are not essentially 

 different from other great modern ship canal locks. The excavation 

 for the Bohio locks is made in a rocky hill against which the south- 

 westerly end of the proposed Bohio dam rests and they are less than one 

 thousand feet from it. 



