PUZZLE IN PANAMA — BOWMAN 



415 



carefully. For one thing, they have built a half-mile-long model of a 

 sea-level canal to the alignment of the present lock canal to test the 

 effect of tides on currents. They have set up criteria for improved 

 alignment, and are having the Navy study the behavior of ships in 

 canal models built to these criteria in the David W. Taylor testing 

 basin at Carderock, Md. They have let design and study contracts in 

 the United States for the development of dredges that can dig at un- 

 precedented depths, as would be necesary in Gatun Lake. And they 

 have recently tested tide-gate and navigation-pass lay-outs in their 

 sea-level model in the Canal Zone. All these activities point to unusual 

 concern with the possibility of converting the present lock canal to one 

 of sea-level type. 



PACIFIC END 

 OF CANAL 



FiGUEE 4. — Maps indicating location 

 relative to present 



of Third Locks Project, begun in 1939, 

 locks. ( See plate 4. ) 



Of the numerous ways by which the conversion could be effected, at 

 least two are known to have been studied, one involving lowering Gatun 

 Lake to sea level in stages, the other lowering it in one operation. 

 They have been called the stage-lowering plan and the deep-dredging 

 plan. 



TO SEA LEVEL BY STAGES 



The essential element of the plan for lowering Gatun Lake to sea 

 level by stages is a temporary lock at each end to permit the passage 

 of traffic at each lowering stage, first from elevation 85 to 50; second 

 from elevation 50 to 20 ; and third from elevation 20 to sea level. The 

 location for these temporary or conversion locks is ready-made in the 

 cuts that were dug for the Third Locks Project, i/^ mile east of the 

 existing Gatun locks at the Atlantic end and % mile west of Mira- 

 flores locks at the Pacific end, although some wideninsr might be re- 



777488—48- 



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