The _frieze_ is a vertical surface, composed alternately of triglyphs and metopes. The _triglyphs_, so called because they are divided into three vertical channels, represent the ends of the primitive longitudinal sills of the cella roof; and a recollection of the woodworker’s craft was still preserved in the chamfer or hollow of their outer edges. The function of the triglyphs was to support the cornice. Generally they were set above and between the columns, but at each end of the entablature one adjoins the corner, thereby increasing the effect of stability. The space between the triglyphs, called the _metope_, was originally left open, except for a wooden shutter to keep out birds. But in the most elaborate examples of later date the metope was decorated with sculpture in high relief. Those of the Parthenon contained groups, representing fights with Centaurs, Amazons, and Trojans. Above the frieze was the cornice, which, as a protection from the drip of the roof, projected to a distance, about one-third of the diameter of a column. Its chief members were a vertical band, known as the _corona_, and an under-part, the _soffit_. The latter sloped down under the corona at about the same angle as the slope of the roof, and was decorated above each triglyph and metope with a _mutule_ or square block, studded with eighteen _guttae_, or drops, a device that recalls the method of making fast the ends of the rafters with wooden pegs. The cornice was carried up the two sloping edges of the roof, but here distinguished by an additional feature, the _cymatium_ or gutter. The triangle or gable thus formed by the three cornices was called the _pediment_. It was embellished at the top and ends with small pedestals, _acroteria_, on which stood figures or conventional ornaments. In a Doric temple the corona, on the sides of the building was without a cymatium, but studded instead with _ante-fixae_, ornaments of terra-cotta or marble, placed opposite the end of each tile-ridge of the roof. The latter, as we have already noted, was covered with tiles of marble or terra-cotta, and finished at the top with ridge-tiles. The mere reading of these details is dry enough. They should be read with an eye on the examples illustrated but also with a mind constantly alert to think out the function and appropriateness of each feature. For the principle of Hellenic construction was that every member should perform a special function. The architect’s logic would not permit him, as we say, to send a boy on a man’s errand or waste a man by employing him at boy’s work, still less to confuse the responsibility for the function between two or more members. Accordingly, the student who is reading intelligently will assure himself at each step as to what particular responsibility was laid upon each member and how appropriately it was fitted to its function.