_May 28th._--The "track" was not always in good order, and the car was "agitated" pretty violently at times, for we were going at a very fair speed over exceedingly sharp curves; in fact, no waggon on the English principle could be expected to remain on the rail at all; and so I had occasion ever and anon to peep out at the stars, for I was shut in and curtained closely in my Pullman, and observed that the country had subsided into a dead waste, treeless, and apparently houseless, through which flowed a broad river, bank-full, and almost on a level with the rail. The line struck the Arkansas at Nickerson, and never left it for hundreds of miles. I awoke at dawn from a troublous sleep, and looked out on the outer world from my secluded couch--on a world so utterly unlike that through which we had passed yesterday, that it was scarcely possible to imagine that we had only travelled through the darkness of one night at the rate of twenty-five miles an hour in the same land. The border line had been passed at "Serjeants," 10 miles east, and we were now in Colorado. Colorado is a vast square, extending from 25° to 35° west longitude, from 37° to 41° of latitude from Washington. It is bounded by New Mexico on the south, Kansas and Nebraska on the east, Wyoming Territory on the north, and Utah on the west. The great mass of the population is concentrated about the middle of the State, at Denver, Leadville, and on the course of the rivers adjacent to the principal mining districts. On the west towards Utah an enormous extent of country is occupied by Indian reservations, and there are also mountain ranges and vast plateaus which, as yet, are unsettled and almost uninhabited. By the side of the rail there spread away to the horizon a plain apparently as flat as the sea itself, but the course and current of the river on our left showed that there was a steady rise to the west; the Arkansas has a fall of 7 feet in the mile, so that we mount westward at that rate till we reach the summit of the great upheaval of the Rockies, the existence of which would not otherwise be cognizable. The plain is covered with tufted grass, the soil is thin and sandy. At long intervals a small wooden shanty. Now and then a roof visible above the level of the plain, covering an excavated dwelling--the solitary window just even with the ground, the doorway buried in a covered way, and the early inhabitant pretty sure to have his or her head thereat to inspect the passing train. Prairie dogs popped up their inquisitive faces. Turkey buzzards soared over the carcases of cattle killed on the line, the number of which must be pretty large, if all the skeletons by the way belonged to the category.