the; locomotives ol ? the lock 



These little electric locomotives, here shown climbing the incline between the middle 

 and upper locks at Gatun, are very powerful and will be used to draw the big ships through 

 the locks. No ship will be allowed to go through the locks under its own steam (see page 

 !73)- Note the men at work on the huge lock gates. 



producing the same condition under 

 which nature has kept the rock sound. 



There can be no question as to excel- 

 lence of the foundation of the locks at 

 Gatun. They are completed and have 

 been subjected to the most trying condi- 

 tions without the slightest settlement or 

 crack. As stated before, all the essential 

 parts are on rocks ; the only exception is 

 the south guide wall, the one that leads 

 into Gatun Lake. This is built on piles 

 and is of as light construction as possible. 

 It has no particular function except that 

 ships will land on both sides of it. 



Prior to the construction of the Gatun 

 locks, many holes were made with a dia- 

 mond-drill outfit into the rock founda- 

 tion to depths of 100 feet or more below 

 sea-level in order to ascertain the charac- 

 ter of the foundation and determine 

 whether or not the rock was sufficiently 

 creviced to transmit pressure from the 



lake to the lock floor. After the holes 

 were bored the ground water showed in 

 them. By pumping the water out of 

 some of the holes and observing to what 

 extent and how quickly the water was 

 lowered in the others, conclusions were 

 drawn as to the probability of the rock 

 being sufficiently creviced to transmit 

 pressure. 



These experiments indicated that mi- 

 nute crevices were in the rock, not 

 enough for the passage of any appre- 

 ciable amount of water, but probably 

 enough to transmit pressure. Conse- 

 quently the floors in the Gatun locks 

 from the emergency dams to the inter- 

 mediate gates of the upper locks are so 

 built that if the full lake pressure does 

 come under them they will stand it. Be- 

 low that, provision is made for carrying 

 any leakage to sea-level through drains 

 behind the lock walls. 



171 



