468 The National Geographic Magazine 



dam at Bohio ; but the trouble with this 

 project is that it entrusts too much to 

 the Bohio dam. If the dam gave way, 

 10 miles of the waterway would disap- 

 pear and the canal would be put out of 

 business for years. 



The investigations of the American 

 engineers during the past two years have 

 brought to light a number of new and 

 important facts which promise to sim- 

 plify the two principal engineering prob- 

 lems connected with the canal : ( 1 ) The 

 control of the torrential floods from the 

 River Chagresand (2) the Culebra Cut. 

 These results are described by Admiral 

 Chester on pages 462-463. The discov- 

 ery that it will be necessary to go down 

 170 feet below sea level instead of 128 

 feet in order to reach bed rock at Bohio 

 makes the plan of the dam at Bohio al- 

 most impracticable. Our American en- 

 gineers have, however, found a better 

 site for a dam at Gamboa, and it is now 

 proposed to construct the dam to control 

 the Chagres floods at this point. The 

 lake thus created would cover about 10 

 square miles and would be entirely out 

 of the canal. 



The building of the dam at Gamboa 

 will not only furnish complete and ef- 

 fective means of control for the Chagres 

 floods, but it has the further advantage 

 of being entirely accessible by the Pan- 

 ama Railroad for the transportation of 

 men and materials. The plan of the 

 dam will probably require a masonry 

 core, with a great mass of earth and 

 rock fill on either side of it, from the 

 waste excavation of the summit cut. 



The conditions attending the con- 

 struction of this dam are in no way un- 

 precedented. The depth of bed rock 

 below water surface is only about one- 

 third that at Bohio and no greater than 

 has already been reached by the use of 

 heavy timber sheet piling for founding 

 masonry structures in the United States. 



The proposed height of this dam from 

 its foundation to its top is far less than 

 found in a number of masonry dams al- 



ready built, and the making of the earth 

 embankments on the two sides of the 

 masonry core is simply wasting the ma- 

 terial from the summit cut. The con- 

 struction of the Gamboa dam, therefore, 

 involves no formidable obstacles not 

 heretofore successfully encountered in 

 engineering practice. 



Experiments made with American 

 steam shovels show that the Culebra 

 Cut can be made in about one-half the 

 time and at about two- thirds the ex- 

 pense formerly estimated. The length 

 of time originally believed necessary to 

 cut Culebra Hill down to sea-level was 

 the reason that the First Isthmian Canal 

 Company recommended a canal with 

 locks. In view of the diminished ex- 

 pense and the great reduction in the 

 estimate of time required for Culebra 

 Cut, general sentiment seems to be that 

 we should construct a sea-level canal and 

 nothing else. But no plan has as yet 

 been definitely adopted. 



WHAT PLAN WILL BE ULTIMATELY 

 ADOPTED IS UNDECIDED 



" I haven't as yet the slightest idea 

 what plan the advisory board will recom- 

 mend for the Panama Canal, and I am 

 certain that not a member of the board 

 has." These were the parting words 

 of a prominent member of the Inter- 

 national Consulting Board of Engineers 

 on the Panama Canal as he stepped on 

 board the steamer which carried the con- 

 sulting engineers to Panama in Septem- 

 ber, 1905. The board had been in ses- 

 sion for several weeks in Washington. 

 It had listened to the various plans sub- 

 mitted by Messrs Bunau-Varilla, Bates, 

 and others, and had digested the results 

 of the past two years' surveys and inves- 

 tigations on the Isthmus by the Walker 

 and Shonts Commissions. But no vote 

 had been taken, nor is any definite de- 

 cision to be sought until the board has 

 been carefully over the ground together. 

 Not a single member of the board is new 

 at the Panama problem ; every engineer 



