The floor of the valley, once a trackless jungle and destined within a short time from the moment that the Boy Scouts gazed upon it to become a mighty lake, was crisscrossed in every direction by lines of railroad along which contractors’ engines were puffing and hauling long winding trains of dirt cars. In places, great steam shovels were at work eating out whole hillsides, taking great mouthfuls at a time.
“Like Tubby eating pie,” laughed Merritt, as he watched one of them.
Across the valley floor, the huge dam, a veritable mountain of concrete, was rising. Busy human ants swarmed everywhere and, at the spot on which the boys stood, with Mr. Mainwaring and some assistant engineers to explain things, hundreds of black workmen were working like beavers on the summit of the great wall. Where they stood the wonderful dam was 100 feet wide, just one-fourth the length of the steamer on which they had come to the Isthmus.
At the base of the dam the width of the gigantic structure is 1,900 feet, and its massive foundations go down into the earth for many feet more.
“Just think,” exclaimed Rob, aglow with the wonder of it all, “before long all this valley floor will be a huge inland sea across which vessels can push their way from Pedro Miguel to Gatun.”
The roar of an excavating machine drowned his comrades’ replies, but their looks showed how deeply they were impressed.
“It makes you feel like a—a fly speck,” exclaimed Tubby, when the uproar ceased for an instant.
Up along a line of rails glided a movable steam shovel. On a side track a busy little locomotive had already bunted a train of flat cars. There was a loud clatter of chains; two white spouts of steam leaped high above the shelter which protected the steam shovel’s engineer from the burning sun. Down swung the huge steel dipper. Almost like a hungry human being, rather like some famished giant, it swung its iron-toothed jaws apart and bit deep into a bank which had to be moved. In an instant its mouth was closed again and the receptacle was full of rough, broken material. Big rocks were among the earth, but that made no difference to this devouring leviathan.
“Hi!” shouted a big shining negro man on the flat car.
The big steam shovel gave a sharp scream of warning, the steam spurted forth again from the vent pipes and up swung the load. The long arm slowly reached out above the flat car. A mighty scampering of the negro loaders followed.