412 ANNUAL REPORT SMITHSONIAN INSTITUTION, 194 7 



is among one of our largest capital assets. What then does it lack? 



First, its present capacity is estimated to be inadequate for com- 

 mercial shipping after 1964, and its locks are not wide enough for 

 modern and future naval vessels. (It was to overcome these dis- 

 advantages that the Third Locks Project was initiated, providing 

 lock chambers 140 feet wide as compared with the present 110 feet.) 

 Second, it may not be safe against modern bombing. These were the 

 items — capacity and security — on which Congress asked to be assured. 



Insofar as capacity is concerned it is certain that the lockage load 

 of the present canal can be increased. The Third Locks Project would 

 do it. Replacement of the existing locks with new ones of larger 

 dimensions and increased efficiency would also do it. Even the in- 

 stallation of a type of gate that could be removed for maintenance 

 and repair (while a temporary gate replaced it) would greatly in- 

 crease capacity by reducing the present overhaul time that keeps one 

 lane of the existing locks out of service 4 months every 2 years. 



The present investigators, however, are believed to favor a fourth 

 way as best meeting the needs of increased capacity and security for 

 the present lock canal. This is by means of the so-called Pacific termi- 

 nal lake plan in which all lock lifts on the Pacific side would be 

 concentrated in the vicinity of Miraflores ; in effect this would elimi- 

 nate the single-life lock at Pedro Miguel, and raise Miraflores to 

 elevation 85 feet so that it would become an integral part of Gatun 

 Lake, connected to it by Gaillard cut. 



To understand this plan, as well as ones proposed to convert the 

 lock canal to one of the sea-level type, it is necessary to have the lay-out 

 of the present 45-mile long canal clearly in mind. Briefly, it consists 

 of a large artificial lake, called Gatun Lake, at elevation 85 feet above 

 sea level, reached by three lock lifts on both the Atlantic and Pacific 

 sides. Ships entering from the Atlantic side, for example, are raised 

 in the Gatun locks whose three lifting chambers, each 110 feet wide 

 and 1,000 feet long, are continuous and in the same structure. They 

 then traverse the lake for some 20 miles in a winding channel 500 to 

 i,000 feet wide that follows the former valley of the Chagres River 

 whose waters have been impounded to form the lake. 



Leaving the lake, ships enter Gaillard cut, 300 feet wide at the bot- 

 tom and 7 miles long, emerging to enter a single-lift lock at Pedro 

 Miguel, which drops them 30 feet to Miraflores Lake at elevation 55 

 feet above sea level. Miraflores Lake is about a mile long, closed 

 at its southern end by Miraflores locks, a two-lift structure in which 

 the ships are lowered to the level of the Pacific Ocean, which is 7 miles 

 farther on. It will be recalled that the single-lock lift at Pedro Miguel 

 was separated from the twin lifts at Miraflores (instead of putting all 

 three together as at Gatun) because of poor foundations at the north 

 end of the Miraflores site. Some of the early canal engineers did not 



