REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


 On the water the production grows in direct proportion to the number of the elements brought in action. With dry works it is far from being proportional, and the individual efficiency decreases rapidly with the increase of the elements associated together, owing to the repercussion of their accidents on each other. This is so true that I have myself been led to reduce the number of dry excavating machines in order to increase the total output.

 GOOD FOUNDATIONS ASSURED FOR THE GAMBOA LOCKS.

 The location of these locks is easy to be found near the Cerro Corrozita, where the summitlevel locks will be placed on the Atlantic side and which is not more than one-third mile distant from the waters of the Gamboa Lake.
 It has been said, in the gray pamphlet, Part IV, among the remarks preceding my letter to the President, that the foundations might not be found. There is nothing of that sort to be feared; the Isthmus around the Gamboa bend of the Chagres is the hardest part of the whole isthmian formation. Everything is rock or rocky clay of the most solid character. There is no risk whatever of not finding the proper location alongside one of the hills connected with the Cerro Corrozita between kilometers 46 and 47.

HOW TO AVOID DIFFICULTY OF CONSTRUCTING THE LOW GAMBOA LOCKS WHEN SUMMIT LEVEL IS REDUCED.

 One question has also been raised, about the practicability of building the locks as the level of the summit gradually decreases.
 There would be no difficulty at all from an engineering standpoint in constructing these locks under protection of cofferdams, or by compressed air, but this would for a long time paralyze the operation of the locks above. For reasons of economy and of speed it is therefore necessary to avoid constructing the lower locks during works of transformation. It is necessary to include the construction of the three lower ones in the programme of the immediate works. They will be constructed at once under easy conditions and everything will be ready for the day of service except the gates. The two upper ones may be left for the future to take care of, as they will be above the water level of the summit. The summit lock will have on the lake side a variable level between 160 feet and 200 feet. The minimum level of the lake will correspond to the momentary suppression of the utility of the lock as a lock, but will not prevent the passage of the scows, which will still find the necessary depth of water in the lock without the necessity of going through the process of locking.
 There will, therefore, result no inconvenience from the variation of the level of the lake for the continuous passage of the scows from the summit level into the Gamboa Lake and vice versa.

 Max imu m L a/e Levc/(20')
 MinimumL.L.6o' (60')
 Wh e ct of te l s 20br8 coawLeivehtof
 Summit
 ~///// (80
 K 450' 40
 ////0,00 sea


 COST OF LAKE GAMBOA LOCKS NOT TO EXCEED $15,000,000.

 We may estimate the extreme cost of these locks by comparing them with the locks of the Comitd Technique. They are of about half their length, the depth of water when the lock is at low stage is also about half that of the Comitd Technique's locks, the fall is greater by onethird, the width is about equal.
 It may be said that under such circumstances it will be very conservative to take the Comit6 Technique's figures as representing the probable cost of these locks. It is a maximum valuation


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