A second rapid followed the first, not far below it, at the end of a broad reach surrounded by high mountains, and although we were not conscious of any great increase in the speed of the current, we heard in a few moments the roar of the Greben rapids--the longest and most difficult of navigation above those at the Iron Gates. As we came near, we saw a line of white water reaching across from shore to shore, apparently without a break. We were speedily approaching this rank of tossing waves, where jets of glittering spray flew high in the air, when we fortunately saw a steamer passing up near the Servian shore, and paddled rapidly across to find the channel, where we would be less likely to meet the only enemy we feared--the whirlpools. Before we had time to deliberate on the best passage among the rocks we were in the midst of the tumbling, dashing waters, and almost before we caught our breath again we were in a comparatively still pool under the immense crag of Greben, which, pushing far out into the stream and narrowing the channel, causes the current to flow with great swiftness over the jagged ledges of rock that dam the river at this point. In our exhilarating dashes through the waves we had not shipped a spoonful of water, although our decks had been constantly awash, even to the very top of the coamings. As we neared the last pitch of the river at this point, we had acquired such confidence in our canoes that we dashed boldly into the roughest of the leaping waves, fired with enthusiasm for the unaccustomed sport, and filled with the excitement of our adventure. The canoes fairly leaped from crest to crest of the billows, and we could not see each other for the screen of dashing spray. A moment or two of active dodging and very hard paddling and we came out breathless at the landing of a temporary station where the international corps of engineers are quartered while the great work of improving the navigation is in progress. CHAPTER XIV The rocky shoulder of Greben is all scarred and torn by the cuttings which are gradually eating off its rugged and dangerous spur. Farther down-stream a breakwater is in course of construction, intended to divert the current from a shallow; and at some distance below, the great black masses of drilling machines, all chains and iron posts and funnels, are seen anchored in mid-stream, where they are constantly at work blasting out a great ledge of rock which causes the rapids of the Jur.