The strength of the current did not seem to be so powerful as I had judged it. However, its determination was difficult. The horse swam with great ease, but he was an extraordinary horse, with a capacity for doing with this apparent ease everything which it pleased him to attempt. I do not know whether this arose from the stirring of larger powers ordinarily latent, or whether the horse's manner somehow concealed the amount of the effort. I think the former is more probable. Half-way across the river, we were not more than twenty yards down-stream from the ferry landing. Ump shouted to turn down into the eddy, and I swung El Mahdi around. A dozen long strokes brought us into the almost quiet water of the great rim to this circle, a circle that was a hundred yards in diameter, in which the water moved from the circumference to the centre with a velocity increasing with the contracting of its orbit, from almost dead water in its rim to a whirling eddy in its centre. I pulled El Mahdi up and let him drift with the motion of the water. We swung slowly around the circle, moving inward so gently that our progress was almost imperceptible. The panic of men carried out in flood water can be easily understood. The activity of any power is very apt to alarm when that power is controlled by no intelligence. It is the unthinking nature of the force that strikes the terror. Death and the dark would lose much if they lost this attribute. The water bubbled over the saddle. The horse drifted like a chip. To my eyes, a few feet above this flood, the water seemed to lift on all sides, not unlike the sloping rim of some enormous yellow dish, in which I was moving gradually to the centre. If I should strike out toward the shore, we should be swimming up-hill, while the current turning inward was apparently travelling down. This delusion of grade is well known to the swimmer. It is the chiefest terror of great water. Expert swimmers floating easily in flood water have been observed to turn over suddenly, throw up their arms, and go down. This is probably panic caused by believing themselves caught in the vortex of a cone, from which there seems no escape, except by the impossible one of swimming up to its rim, rising on all sides to the sky. In a few minutes El Mahdi was in the centre of the eddy, carried by a current growing always stronger. In this centre the water boiled, but it was for the most part because of a lashing of surface currents. There seemed to be no heavy twist of the deep water into anything like a dangerous whirlpool. Still there was a pull, a tugging of the current to a centre. Again I was unable to estimate the power of this drag, as it was impossible to estimate how much resistance was being offered by the horse.