National Geographic : 1914 Feb
THE LOCOMOTIVES OF 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 173). 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.