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THE NATIONAL GEOGRAPHIC MAGAZINE 



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CROSS-SECTION OF LOCK CHAMBER AND WALLS, GATUN LOCKS 



A. Culvert in center wall. E; Culvert in side wall. 



B. Connections between center and lateral F. Drainage gallery. 



culvert. G. Gallery for electric wires. 



C. Lateral culvert. H. Passageway for operators. 



D. Wells opening from lateral culverts into lock chamber. 



There will be three main culverts extending the full length of the locks, one in each of 

 the side walls and one in the middle wall. The side-wall culverts are 22 feet in diameter 

 from the intake at the south end of the upper locks to a point 320 feet north, where they are 

 reduced to 18 feet, at which diameter they will continue to the end, a distance of about 3,500 

 feet. The culvert in the middle wall is 22 feet in diameter from its south end to a point 120 

 feet north, where it also will be reduced to 18 feet, at which diameter it will continue to the 

 end, a distance of about 3,600 feet. Lateral culverts in the form of an ellipse will run in the 

 floor from and at right angles to the'main culverts at intervals of 32 and 36 feet, leading 

 alternately from the side and middle culverts. Water will be delivered or collected by each 

 lateral culvert through five openings or wells in the floor. Valves, which may be opened or 

 closed either individually or all at one time, will be located at the intakes and outlets of the 

 main culverts, and at the connections between the center culverts and the lateral culverts 

 (see page 205). In the center space of the middle wall there will be a tunnel, divided into 

 three stories or galleries. The lowest gallery is for drainage ; the middle, for the wires that 

 will carry the electric current to operate the gate and valve machinery, which will be installed 

 in the center wall, and the top, a passageway for the operators. 



therefore, selected as being the cheapest 

 and most expeditious method of hand- 

 ling the loam, especially because by this 

 means 450 acres of swamp land adjacent 

 to the canal could be reclaimed. Four 

 hydraulic pumps force water through 

 pipes, fitted with hydraulic giants or 

 monitors, with a pressure of 130 pounds 

 per square inch at the nozzles ; these jets 

 wash the loam to sumps, from which 

 18-inch centrifugal dredging pumps, 

 mounted on reinforced concrete barges, 

 pump the material to such places as may 

 be desired. 



Below the area to be excavated in this 

 manner, the channel is secured by ordi- 

 nary dredging operations. Rock en- 

 countered is blasted, the drilling being 

 done by churn drills through the natural 

 surface to the proper depth or, where 



submerged, by use of a drill scow. A 

 Lobnitz rock breaker is also in use for 

 preparing the rock for the dredges. The 

 total amount of material to be excavated 

 aggregates 35,000,000 cubic yards, of 

 which 73.55 per cent is completed. 



REBUILDING THE RAILROAD 



The relocated Panama Railroad is be- 

 ing pushed forward so as to keep pace 

 with canal construction work. From 

 Colon to Mindi and from Corozal to 

 Panama, the old line, relieved of some 

 of its curvature, will be used, but the re- 

 mainder must be rebuilt. From Mindi 

 to Gatun, two miles, and from Paraiso 

 to Corozal, four miles, the new line is 

 completed and is being operated. 



Just south of Miraflores the new road 

 passes through a tunnel 800 feet long. 



