To return to the wheel--now really and substantially a wheel, but which has still to be turned so as to run perfectly true upon the metals--it is conveyed to the wheel lathe, and affixed to what looks like another wheel, which is set in motion by steam-power, and carries our wheel round with it. A workman sets a tool to plane its edge, which shaves off the steel as if it were wood, and reduces it to the prescribed scale. Then, when its centre has been bored to receive the axle, the genesis of the wheel is complete, and it enters upon its life of perpetual revolution. How little do the innumerable travellers who are carried to their destination upon it imagine the immense expenditure of care, skill, labour, and thought that has been expended before a perfect wheel was produced. Next in natural order come the rails upon which the wheel must run. The former type of rail was a solid bar of iron, whose end presented a general resemblance to the letter [T], which was thick at the top and at the bottom, and smaller in the middle. It was thought that this rail was not entirely satisfactory, for reasons that cannot be enumerated here, and accordingly a patent was taken out for a rail which, it is believed, can be more easily and cheaply manufactured, with a less expenditure of metal, and which can be more readily attached to the sleepers. In reality it is designed upon the principle of the arch, and the end of these rails somewhat resembles the Greek letter [Omega], for they are hollow, and formed of a thin plate of metal rolled into this shape. Coming to this very abode of the Cyclops, the rail-mill, the first machine that appears resembles a pair of gigantic scissors, which are employed day and night in snipping off old rails and other pieces of iron into lengths suitable for the manufacture of new rails.