REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


upon the depth of the water. The same conditions exist in a large part of the Rio Grande delta, and the construction of even a low barrage would undoubtedly encounter innumerable difficuties in crossing localities where the subformation would be such as to give way under the imposition of the weight of the material placed thereon. The same obstacle would probably be met to a greater or less extent in the construction of a dam, particularly a high one, in the vicinity of Gatun. The entire valley to at least a depth of 200 feet is alluvial. It is, therefore, highly improbable that in the heterogeneous mass of material with which the ancient gorge is filled, particularly near the surface, that unforeseen difficulties in securing proper foundations would not be encountered.
 Coming to Bohio, while it is not impracticable to construct a dam at this locality, the fact that bed rock was found at a point 167 feet below sea level, overlaid at the greater depth by material of a freely water-bearing nature, renders the construction at this site undesirable. Though possible, it involves experimental methods, the cost and result of which are as yet undetermined quantities.
 In the opinion of the writer, the Gamboa dam furnishes the key to a practicable solution of the problem, and while an absolutely necessary adjunct to the sea-level project, it will also fit in with any low-level lock plan not involving the creation of an intermediate navigable lake of such size as to afford absolute control of the Chagres and other floods. Should even a plan be adopted for approximately a 50 or 60 foot summit-level elevation involving a dam at Bohio containing a lake of moderate dimensions, the construction of some dam either at Gamboa or Alhajuela would be necessary; in the opinion of the writer, preferably at Gamboa. This dam would be adjacent to the line of the canal for inspection and regulation, would furnish ample electric power, which should be made available to assist in the construction of the canal and also its maintenance and operation, and afterwards would furnish a water supply and sufficient electrical current to provide for lighting and other public utilities along the route of the canal, including its towns and cities.
 The construction of the Gamboa dam would satisfactorily solve the control of the Chagres River, which would resolve itself simply into the question of taking care of and controlling the average and not the maximum floods of the Chagres, properly constructed spillways, supplemented with diversion channels and utilizing the canal prism with its outlets to two oceans, performing this work.
 While the construction of a tunnel spillway through the mountain range, or an open cut to act as a natural automatic spillway, discharging the surplus floods into the upper valley of the Gatuncillo on the Caribbean slope, might be desirable, it is not an absolute necessity for the sealevel plan.
 The estimates which have heretofore been made for the construction of the Gamboa dam for the control of the Chagres, even including the tunnel spillway and all the diversion channels combined, do not exceed 10 per cent of the cost of even the sea-level canal. In considering the various.difficulties which combined make up the time of accomplishment of any engineering work, their relative importance can properly be held to be the percentage such factors bear to the whole; the formula is practically a plus b plus c plus n equals accomplishment. An item in the equation of value not to exceed one-tenth of the whole should certainly not be an absolutely deciding deterrent element.
 It may be well to repeat and again emphasize a few factors which the writer considers either essential or desirable:
 1. That as a strait at Panama unobstructed would place the least retrictibn to commerce, the sea-level canal is the ideal plan.
 2. No plan should be adopted that would ultimately prevent the completion of a sea-level canal should future demands and necessities require it.
 3. No high dam should be constructed the foundations of which can not be carried to bed rock, or an impervious curtain wall constructed practically accomplishing the same purpose.
 4. No high dam should be' constructed the destruction of which by man or nature would prevent the use of the canal until its restoration had been effected.


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