The Romans adopted the column and beam system of the Greeks, and joined to it the arch and vault. The union of the two elements of arch and beam is the keynote of the Roman style. In this style the orders were used more for decoration than for construction, and were superposed, or set one upon the other, dividing the buildings into stories.

The five Roman orders are shown in Fig. 2. A is the Tuscan; B, the Doric; C, the Ionic; D, the Corinthian; and E, the Composite. In each of these, a', b', and c' represent the pedestal, column, and entablature, respectively. For comparison, the relative values of the lower diameters of the shafts, when the orders are profiled to a uniform total height of 31 ft. 8 in., is given in Table II.

The Roman Orders 373

Fig. 2.

Table II. Roman Orders. With Uniform Altitude = 31ft. 8 In

Title.

Index Letter on Fig. 2.

Lower Diameter of Shalt.

With Pedestal.

Without

Pedestal.

Tuscan ..........................

A

2 ft. 10 1/4 in.

3 ft. 7 7/16 in.

Doric .............................

B

2 ft. 6 in.

3 ft. 2 in.

Ionic ............................

C

2 ft. 2 5/8 in.

2 ft. 9 3/4 in.

Corinthian ....................

D

2 ft. 0 in.

2 ft. 6 3/8 in.

Composite......................

E

2 ft. 0 in.

2 ft. 6 3/8 in.

Table III gives the relative measurements, with respect to the module, or semi-diameter of the shaft, for proportioning the Roman orders, and is valuable for consultation when preparing preliminary designs, the reference letters being those shown in Fig. 2. _______