REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


 The two following sketches represent the flight before the transformation and the flight after the upper lock has been erased and the summit level lowered 45 feet.
 A



 a Ilk
 3 35




 >7O<
 rig.
 mourner u Nmit Level

 Former Bottom.
 of $m/nit Lvel\ Ae u4Sarnrnt LeVel fB

 New Bottom of C M C

 35
 Fig.2. yitlei <70o70<70
 The same principle which we laid before will lead us to the solution. We must liberate from one another every organ of the summit level and every organ of the lower lock.
 A first solution similar to the one already described appears at first glance.
 If, instead of building the lower gate of the upper lock from A to C we make a gate extending from A to D, and if we limit the bottom of the upper lock by a wall placed in M N instead of C D (the distance between C D and M N being about TO feet), we shall have reproduced the conditions described for the single lock. (
 When the upper lock will have been razed, its bottom will form the extremity of the new summit level, and this extremity being free from the upper gate of the lower lock and at a distance of 70 feet, can be, like the rest of the summit level, gradually lowered without affecting the lock in any way.
 Some more precaution only will have to be taken to prevent any stone from falling near the gate. It is useless to insist upon these details; every engineer conceives the precaution for hammering the masonry and carefully taking away the debris, not with dredges but with movable compressed-air caissons or divers. It is sufficient that a distance of 70 feet be reserved between the wall and the gate to prevent any accident through neglect.
 This solution has the great disadvantage of requiring the construction of a gate of abnormal height: 45+45+35=125 feet. Therefore, we only mention it for the purpose of following the trail of the principle.
 A much better solution can be had by prolonging the lower lock for 70 feet. This enables us to prepare all the masonry and the place necessary for the installation of two gates respectively 70 feet ahead of the two corresponding gates of the lower lock.
 a The working capacity of one single lock is nearly twice as great as that of a flight of two locks of the same dimensions. (See my book of 1892.) When the upper lock will be no more useful, one of the twin single locks remaining will accommodate as much transit as the twin flights before, thereby giving all facilities to remove the masonry of one of the upper locks, while the lower lock of the other flight will do all the work of the transit.
 465A-06- 15


225