REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


section indicates the surface of the ground, but, unfortunately, does not show the rock or other solid foundation. If a dam were built here, impounding the water to an elevation of 90 feet, then, of course, the Bohio dam and the locks and spillway would be omitted, and locks would be built at Gatun.
 The length of the dam would be 6,750 feet, while the length of the Bohio dam is 2,546 feet. The area of the section is nearly three times that at Bohio; therefore it might not be out of the way, for the present, to say that the cost of the Gatun dam would possibly be three times that estimated for the Bohio dam, or $19, t08,920. At present, there seems to be no reason to think that the locks would cost more at one place than at the other, but the spillway should be somewhat longer, and might cost more. There may be a question whether the hills to the west of Gatun are high enough to contain the Gatun Lake at an elevation of 90 feet, but the raised map made by the New Panama Canal Company, a reproduction of which is to be seen at Columbia University, indicates sufficiently high ground. The lake would extend far up the valley of the Rio Gatun on the east and the Rio Trinidad on the west, and submerge the Chagres Valley for 9 miles, including the Aqua Clara, Peia Blanca, Vino Tinto, and Bruja swamps, cover 20 or 30 square miles of swampy land, and thus improve the healthfulness of the country. This lake area added to the 38.5 square miles of the Bohio Lake would be a benefit in every way and would render the Alhajuela dam on the upper Chagres unnecessary. Between Gatun and Bohio the excavation of the sea-level canal, the Pefia Blanca Swamp outlet to Aqua Clara Swamp, the Chagres diversion from Aqua Clara Swamp to near Gatun, and the diversion of the Rio Gatun would become unnecessary and their cost would be saved. These items amount to $14,635,604, a sum large enough to pay the assumed extra cost of the Gatun dam and leave about $2,000,000 to pay for changing the line of the Panama Railroad and the possible additional cost of the spillway. If these assumptions should prove practicable, the result would be a better and safer canal, shorter time of transit, and more healthy conditions, all at no greater cost, and with lower maintenance charges.
 If a dam at Gatun with an elevation of 90 feet were found inadvisable, one of 45 feet elevation might be built and the Bohio dam and lake retained. Then the lower Bohio lock would be omitted and established at Gatun and a spillway built there also. The cost of the 45-foot Gatun dam might be assumed at $12,000,000, about twice the estimated cost of the Bohio dam. Its length would be 5,150 feet. The head on the Bohio dam would be reduced from 90 to 45 feet, and the danger from seepage greatly reduced.
 It seems quite possible that with this 45-foot dam the total cost of the 'anal would be reduced a few million dollars below the figure named in the report of the Isthmian Canal Commission.
 Turning from the Colon end of the canal to the Panama end, it appears that from the Miraflores locks to La Boca, a distance of 4.12 miles, the canal is to be excavated at sea level through a low swampy country, with occasional rock, at a cost of $10,963,458. It is suggested, as a plan worth consideration, that this lock be located at La Boca, that a dam and spillway be built there, and that the 4.12 miles of swamp be thus flooded, thus affording better and safer navigation than would be had in a narrow channel. The main dam would probably be a mile long, with two or three shorter dams, and might cost no more than the excavation of the 4.12 miles of canal that would be saved. The malarial swamps would be submerged, also. With the 20-foot rise and fall of tide at Panama, the inrush and outrush of the water in that 4.12 miles of sea-level canal might incommode navigation. All this would be done away with if the last lock was placed at La Boca.
 Recurring to the suggested 45-foot Gatun dam, with its large lake, the plan of reducing the elevation of the summit level from 90 to 45 feet may be briefly considered. This elevation is suggested, as 45 feet seems to be the maximum permissible lift for a lock.
 The elevation of 90 feet for the Bohio dam sees to have been selected with reference to flood control and in order that the resulting lake should have an area large enough to supply water for lockage, seepage, and evaporation during the dry months, without too great a change in the elevation of the surface of the lake.
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