To be accurate, it took our hero quite a little while to grasp the significance of all that he saw, for the Culebra cut extends through nine miles of rocky soil, and at the period of his inspection it had already bitten deep into the hilly ground which barred the onward progress of the canal at Obispo. One ought to say, in an endeavour to give facts accurately, that this mass of material forms the southern boundary of the huge Chagres valley which, when the works are completed, will be flooded with water. It bars all exit there, though by turning sharply to the left one may follow the course of the river through a narrow, ascending valley. However, the scheme of the undertaking required that there should be no sharp bends, and in consequence the host of workers were toiling to cut a gigantic trench, of great width and enormous depth, right through this hilly ground. What Jim saw was somewhat similar to the works below Gatun, at the Colon end of the canal, but vastly magnified. There were the same terraces, with tracks of rails laid, bearing an endless procession of spoil trains and numbers of steam diggers. There was the same pilot cut in the very centre, from which the terraces ascended step by step, as if they were portions of another Egyptian pyramid. But there comparisons ceased. This huge ditch extended for nine miles, and throughout its length presented an army of toilers, any number of dirt trains, and a constant succession of white steam billows, at various elevations, pointing to the places where the hundred-ton diggers were at work. "You have to get right on the spot to see what's happening," said Phineas, looking proudly about him. "You can see for yourself now that it means everything to us to get rid of the dirt as quickly as possible, and everything to have spare trains ready to fill the place of those taking the spoil away. This concern is simply a question of dirt, and of how rapidly we can shift it. If I was the President of the Republic of the United States himself I should have to look lively all the same, and dodge about so as not to get in the way of the dirt trains. But we'll get out here and climb; I'll show you a thing or two." He chuckled at the prospect before him, for to expatiate on the canal works to a keen young fellow, such as Jim undoubtedly was, was the height of enjoyment to the energetic official. Their car was switched on to a side track at once, and, descending from it, the two clambered up the scarped side of the trench till they were on the summit of the rocky ground. Then it was possible to obtain a bird's-eye view of the whole cut, and to appreciate its vastness. Jim noticed that the path he had clambered by shelved rather gently, while elsewhere the bank of the trench was steeply scarped, and at once drew Phineas's attention to the matter.