18. _Orders of architecture._--By the architectural orders are understood certain modes of proportioning and decorating the column and entablature. They were in use during the best days of Greece and Rome, for a period of six or seven centuries. The Greeks had three orders, called the _Doric_, the _Ionic_, and the _Corinthian_. These were adopted and modified by the Romans, who also added two others, called the _Tuscan_ and the _Composite_. 19. _Doric order._--The Doric is the oldest and most massive order of the Greeks. The column, in the examples at Athens, is about six of its diameters in height; in those of an earlier date, it is but four or five. The temple here adduced to illustrate this order was built by Cimon, son of Miltiades, about the year 450 before Christ. It is said to be in a state of better preservation than any other of the ancient Greek edifices at Athens. It will be seen that the shafts are _fluted_, that is, cut in semicircular channels, in a longitudinal direction. The United States' Bank, at Philadelphia, is a noble specimen of this order. [Illustration: THE TEMPLE OF THESEUS.] 20. _Ionic order._--This order is lighter than the Doric, its column being eight or nine diameters in height. Its shaft has twenty-four or more flutings, separated from each other by square edges; and its capital consists, in part, of two double scrolls, called _volutes_, usually occupying opposite sides. These volutes are supposed to have been copied from ringlets of hair, or from the horns of the god Jupiter Ammon. The following example of this order consists of three temples, each of which was dedicated to a different individual, viz., Erectheus, Minerva Polias, and the nymph Pandrosus. [Illustration: THE ERECTHEUM AT ATHENS.] 21. _Corinthian order._--The Corinthian is the lightest and most decorated of all the Grecian orders. Its column is usually ten diameters in height, and its shaft is fluted like that of the Ionic. Its capital is shaped like an inverted bell, and was covered on the outside with two rows of the leaves of the plant acanthus, above which are eight pairs of small volutes. It is said that this beautiful capital was suggested to the sculptor Callimachus by the growth of an acanthus about a basket, which had been accidentally left in a garden. 22. The Greeks sometimes departed so far from the strict use of their orders, as to employ the statues of slaves, heroes, and gods, in the place of columns. A specimen of this practice is exhibited in the cut illustrative of the Ionic order. It belongs to the temple dedicated to Pandrosus.