This told the geologist that his unsuspecting Sanusian was located in an aircraft much like the other. The same tremendous noise of the engine, the same inexplicable wing action, together with the same total lack of the usual indications of human occupancy, all argued that the two men had hit upon the same type of agent. In Van Emmon's case, however, he could occasionally glimpse two loose parts of the machine, flapping and swaying oddly from time to time within the range of the observer, and at the front. Nothing was done about it. Van Emmon came to the same conclusion as Smith; the operator was looking into something like a periscope. Perhaps he himself did not do the driving. From what the geologist could see of the country below, it was quite certainly cultivated. In no other way could the even rows and uniform growth be explained; even though Van Emmon could not say whether the vegetation were tree, shrub, or plant, it was certainly the work of man-or some-thing mightily like man. Shortly he experienced an abrupt downward dive, such as upset his senses somewhat. When he recovered, he had time for only the swiftest glance at what, he thought rather vaguely, was a great green-clad mountain. Then his agent brought the craft to one of those nerve-racking stops; once more came a swimming of the brain, and then the geologist saw something that challenged his understanding. The craft had landed on the rim of a deep pit, or what would have been called a pit if it had not been so extraordinary. Mainly the strangeness was a matter of color; the slope was of a brilliant orange, and seemingly covered with frost, for it sparkled so brightly in the sun as to actually hurt the eyes. In fact, the geologist's first thought was "A glacier," although he could not conceive of ice or snow of that tint. Running down the sides of the pit were a number of dark-brown streaks, about a yard wide; Van Emmon could make them out, more or less clearly, on the other side of the pit as well. From the irregular way in which the walls were formed, he quickly decided that the pit was a natural one. The streaks, he thought, might have been due to lava flow. His agent proceeded to drive straight over the rim and down the slope into the pit. His engine was quite stopped; like Smith, the geologist wondered just how the craft's wheels were operated. Next he was holding his breath as the machine reached so steep a point in the slope that, most surely, no brakes could hold it. Simultaneously he heard the hiss and whine which seemed to indicate the suction device. "It was a whole lot like going down into a placer mine," the geologist afterward said; and in view of what next met his eyes, he was justified in his guess. Down crept the machine until it was "standing on its nose." The sun was shining almost straight down into the slope, and Van Emmon forgot his uneasiness about the craft in his interest in what he saw.