On the following day they commenced the exploration of the Colorado River. From this starting point it was about seven hundred miles to the foot of the Grand Cañon. Through the entire series of cañons the river tumbled down more than 5,000 feet. The lecturer here stated that the fall of the Mississippi from Cairo down was about four inches to the mile, and of the Ohio some eight inches, and that the Colorado carried about as much water as the Ohio at Louisville. In some places the river was wide, and here its fall did not exceed that of the Ohio or Upper Mississippi. The fall in Marble Cañon, however, was from ten to three hundred feet to the mile! The boats, with the exception of the one in which he and Major Powell traveled, were about twenty-two feet long and decked, so that there were three water-tight compartments in each boat. His boat, in which were two other men, was only sixteen feet in length. This led the way, while the other boats, laden with provisions, etc., followed. The roar of the water in the cañon could be heard a long way off. The chief difficulty in navigating was riding the waves, which differed greatly from that of the sea. In the case of the latter the water remained, simply rising and falling, while the _form_ alone rolled on; but in the former the water of the wave rolled on, the form being fixed. As long as the boat could be kept on the waves, all was well, but the great tendency was to drift into the whirlpool in the center. Three miles below the junction of the Grand and the Green rivers appeared a series of rapids and falls, and nearly two weeks were spent in running through this difficult portion of the river. Having passed through Cataract Cañon, they encountered Narrow Cañon, where the river for seven miles rushed down a steep declivity. Seven miles again below a stream came in on the right side. Up this the leading boat went, and one of the men, in reply to a query from another in one of the boats following, as to the nature of the water in this new stream, called out, “A dirty devil,” and by that name it was designated on the maps. It was a stream of red mud, having along its course hot mineral springs. The odor was fetid and foul, resembling, as the lecturer graphically described it, “One of those alabaster boxes of ointment with which they used to anoint abolitionists in the brazen days of yore.” Below Narrow Cañon was Glen Cañon, stretching for a hundred and fifty miles through homogeneous sandstone of a beautiful color, its walls often perpendicular and indented with glens, alcoves and caves. The latter were formed by the rain-showers running down the sides of the wall, and slowly eating them away. At the foot of the homogeneous sandstone was a soft, friable, crumbling sandstone, and through this the river had cut some fifty miles of its course. In the next cañon—Marble Cañon—was a series of cataracts and rapids which made progress very difficult. Here the falls were too steep to be “run,” and