a famous historical column erected in Rome, in honour of the emperor Trajan. It is of the Tuscan order, though something irregular; its height is eight diameters, and its pedestal Corinthian: it was built in a large square there, called Forum Romanum. Its base consists of twelve stones, of an enormous size, and it is raised on a socle, or foot of eight steps; within side is a stair-case, illuminated with forty four windows. It is 140 feet high, which is thirty-five short of the Antonine column, but the workmanship of the former is much more valued. It is adorned from top to bottom with bas-reliefs, representing the great actions of that emperor against the Daces.

TRAJECTORY of a comet, is its path or orbit, or the line it describes in its motion. See Astronomy, p. 444.