PANAMA CANAL LOCKS. 



175 



example is shown by Figs. 156 to 160, designed and partly 

 constructed by M. Eiffel, present many points of originality. 

 The length from centre to centre of the caisson chambers is 

 652 feet 2 inches, and the clear length on the floor 584 feet. 

 The width at the coping level is 67 feet 7 inches, and at the 

 bottom 44 feet 7 inches, by a depth, from coping level to the 

 floor, of 68 feet 1 inch. The depth of water over the lower 

 sill with the lock fall is 62 feet 4 inches, and over the upper 

 sill 27 feet 1 inch. These dimensions are sufficient to allow of 

 the admission of the largest types of trans-Atlantic steamers. 

 The sections show the excavations in the solid rock ; where, 



FIG. 155. 



however, the ground proved unfavourable, the sides and bottom 

 would be lined with masonry. 



The entrances are shown to be constructed with iron caissons 

 recessed into the rock and filled with concrete. The sides are 

 vertical, and the width 61 feet 6 inches. 



A very special feature in these locks is the method adopted 

 by M. Eiffel for the admission and discharge of the water. 

 This is effected by two lines of iron pipes about 13 feet in 

 diameter, laid in grooves cut in the bottom of the lock 

 and extending from end to end, and terminating outside the 

 entrances where the openings for the admission or discharge 

 of the water are controlled by valves. These mains are set 

 in concrete with the upper side just beneath the floor of the 

 lock, except under the entrances, where they are buried entirely 

 beneath the concrete. 



