CŎLUMBĀRĬUM, a dovecot or pigeon-house, also signified a sepulchral chamber formed to receive the ashes of the lower orders, or dependants of great families; and in the plural, the niches in which the cinerary urns (_ollae_) were deposited. [Illustration: Ancient Columns.] CŎLUMNA (κίων, στύλος), a pillar or column. The use of the trunks of trees placed upright for supporting buildings, unquestionably led to the adoption of similar supports wrought in stone. As the tree required to be based upon a flat square stone, and to have a stone or tile of similar form fixed on its summit to preserve it from decay, so the column was made with a square base, and was covered with an _abacus_. [ABACUS.] Hence the principal parts of which every column consists are three, the base (_basis_), the shaft (_scapus_), and the capital (_capitulum_). In the Doric, which is the oldest style of Greek architecture, we must consider all the columns in the same row as having one common base (_podium_), whereas in the Ionic and Corinthian each column has a separate base, called _spira_. The capitals of these two latter orders show, on comparison with the Doric, a much richer style of ornament; and the character of lightness and elegance is further obtained in them by their more slender shaft, its height being much greater in proportion to its thickness. Of all these circumstances some idea may be formed by the inspection of the three accompanying specimens of pillars. The first on the left hand is Doric, the second Ionic, and the third Corinthian. In all the orders the shaft tapers from the bottom towards the top. The shaft was, however, made with a slight swelling in the middle, which was called the _entasis_. It was, moreover, almost universally channelled or fluted. Columns were used in the interior of buildings, to sustain the beams which supported the ceiling. Rows of columns were often employed within a building, to enclose a space open to the sky. Beams supporting ceilings passed from above the columns to the adjoining walls, so as to form covered passages or ambulatories (στοαί). Such a circuit of columns was called a _peristyle_ (περίστυλον), and the Roman _atrium_ was built upon this plan. The largest and most splendid temples enclosed an open space like an atrium, which was accomplished by placing one peristyle upon another. In such cases, the lower rows of columns being Doric, the upper were sometimes Ionic or Corinthian, the lighter being properly based upon the heavier. A temple so constructed was called _hypaethral_ (ὕπαιθρος). But it was on the exterior of public buildings, and especially of temples, that columns were displayed in the most beautiful combinations, either surrounding the building entirely, or arranged in porticoes on one or more of its fronts. [TEMPLUM.] Their original and proper use was, of course, to support the roof of the building; and, amidst all the elaborations of architectural design, this object was still kept in view.