186 



THE NATIONAL GEOGRAPHIC MAGAZINE 



CULEBRA CUT, LOOKING NORTH 



erals leading from the center wall by 

 cylindrical valves. 



Assuming a difference of head of 30 

 feet, it is estimated that the entire lock 

 can be filled or emptied, using one cul- 

 vert in 15 minutes and 42 seconds, and 

 in 7 minutes and 51 seconds when both 

 culverts are used. 



The lock gates are of the mitering 

 type, double leaf, straight gates, vary- 

 ing in height from 45 feet 7 inches to 79 

 feet ; the length of each leaf is about 65 

 feet. A contract has been entered into 

 for furnishing the steel for the gates 

 and for their erection in place by June 

 i, 1913. To meet this condition, it is 

 necessary that the concrete work shall 

 be completed in time to enable the con- 



tractors to begin the erection of the 

 various sets of gates on the dates speci- 

 fied in their contract, and the work is 

 being prosecuted with this end in view. 

 To accomplish the result, the concrete 

 for the Gatun locks must be finished by 

 June 1, 1912, and that for the locks on 

 the Pacific side by October of the same 

 year. 



SAFETY DEVICES 



It has been accepted as a fundamental 

 feature of the design that at each flight 

 of locks there must always be two bar- 

 riers separating the high level from the 

 level next below. To carry this out, two 

 sets of mitering gates are placed at the 



