THE PANAMA CANAL 



179 



TRACK-RAISING AND SHIFTING MACHINE 



This powerful machine lifts the track and ties clear of the ground and then deposits 

 them from three to nine feet away. It "bends the steel rails as easily as if they were made 

 of clay (see page 177). 



will be exposed to the maximum head 

 of 85 feet, the remainder to less. 



The dimensions of the dam have been 

 criticised as excessive and unwarranted, 

 but its designers considered it desirable, 

 in view of the amount of material avail- 

 able, that ample provisions be made 

 against every force which may affect its 

 safety, and that a barrier be made so 

 that the layman without engineering 

 knowledge would recognize its stability. 

 Now that the dam is assuming appreci- 

 able proportions, this latter object is 

 more than realized. 



The dam in plan is a broken line to 

 conform to the configurations of the 

 natural surface, thereby materially re- 

 ducing the fill. It extends from the hill 

 in which the locks are to be constructed 



to Spillway Hill, thence along the spur 

 or hog-back of the hill on the west side 

 of the valley (see map, page 201). 



The adoption of the earth dam brought 

 on such criticism that an exhaustive ex- 

 amination of the foundations was made 

 in order to determine more carefully the 

 character and extent of the various under- 

 lying materials ; to ascertain whether 

 there was any possible connection be- 

 tween the swamp areas to the north and 

 south through the deposits in the gorges 

 across which the dam will be built ; for 

 testing the ability of the material to sup- 

 port the proposed structures, and for 

 learning whether suitable material for 

 the dam could be obtained in the im- 

 mediate vicinity. 



As the result of the investigations, it 



