THE PANAMA ROUTE FOR A SHIP CANAL. 553 



Aftei leaviiiij; Bobto Luke at Obispo a tlight of two kx-ks is found 

 at Pedro Miguel, about- 7,9 miles from the former or '21h miles from 

 Bohio. These locks have a total ordinary maximum lift of 60 feet, 

 divided into two lifts of 30 feet each. The fifth and last lock on the 

 route is at Miratiorcs. The average elevation of water between Pedi-o 

 Miguel and Miratiores is ;:>0 feet above mean sea level. Inasmuch as 

 the range of tide between high and low in Panama Ba}" is about 20 

 feet, the maximum lift at ]\Iiratlores is 40 feet and the minimum about 

 20. The twin locks at Miratiores l)ring the canal surface down to the 

 Pacific Ocean level, the distance from those locks to the 0-fathom 

 curve in Panama Ba}' being 8.54 miles. There are therefore five locks 

 on the Panama route, all arranged on the twin plan, and, as on the 

 Nicaragua route, all are founded on rock. 



Near Obispo a pair of guard gates are arranged '' so that if it should 

 become necessary to draw off the water from the summit cut the level 

 of Lake Bohio would not l)e affected." 



An unprecedented concentration of heav}" cutting is found between 

 Obispo and Pedro Miguel. This is practically one cut, although the 

 northwesterly end toward Obispo is called the Emperador, while the 

 deepest part at the other end, about 3 miles from Pedro Miguel, is the 

 great Cule])ra cut, with a maximum depth on the center line of the canal 

 of 286 feet. On page 93 of the Isthmian Canal Commission's report 

 is the following reference to the material in this cut: " There is a little 

 ver}" hard rock at the eastern end of this section, and the western 2 

 miles are in ordinary materials. The remainder consists of a hard 

 indurated clay, with some softer material at the top and some strata 

 and dikes of hard rock; In fixing the price it has been rated as soft 

 rock, but it must be given slopes equivalent to those in earth. This 

 cut has been estimated on the basis of a ])ottom width of 150 feet, with 

 side slopes of 1 on 1.'' When the old Panama Canal Company ))egan 

 its excavation in this cut considerable difiiculty was experienced by 

 the slipping of the material outside of the limits of the cut into the 

 excavation, and the marks of that action can be seen plainly at the 

 present time. This experience has given an impression that nmch of 

 the material in this cut is unstable, but that impression is erroneous. 

 The cla>' which slip})ed in the early days of the work was not drained, 

 and, like wet clay in numerous places in this country, it slipped down 

 into the excavation. This matei'ial is now drained and is perfectly 

 stable. There is no reason to anticipate any future difiiculty if reason- 

 able conditions of di'ainage are maintained. The high faces of the cut 

 will probably weatiier to some extent, although experience with such 

 cla}^ faces on the isthmus indicates that the amount of such action will 

 be small. As a matter of fact, the material in which the Culebra cut 

 is made is stable, and will gi\(' no sensible dilficulty in maintenance. 



Throughout- the most of the distance between Colon and Bohio on 



