Of all the great modern innovations, the railroad probably is the one to which American artists have accorded the largest significance. The passenger railroad first appeared on the American scene in the 1830s, and it almost immediately caught the eye of several of the nation's most gifted landscape painters. By the time of the Civil War the new machine already had been incorporated into the work of Thomas Cole, Thomas Doughty, Asher Durand, and John Kensett. The subject attracted their attention, for one thing, because of its newness — its radically innovative character-and, for another, because of its compelling visual properties. A steam-powered locomotive moving across the landscape is an arresting sight-so arresting, indeed, that its visual character alone might seem to account for the strong hold it so quickly took on the imagination of artists. Here, after all, was an imposing, mobile, man-made contrivance, a complicated mechanism wrought of dark metal in various shifting sharp-edged geometric forms; the engine's motive power was made visible by the train of cars it pulled, the surging puffs of smoke and steam (black or white or both) that trailed behind it, and the intermittent flashes of red when its fire box was open.