49. There are two styles of the Doric Order, the Denticular Order and the Alutular Order. The difference between these two styles is purely decorative and will be explained in the course of this analysis. • 50. The Doric column, more elegant than that of the Tuscan Order, is sometimes fluted with segmental channels, the intersec tion of which forms a sharp raised edge or "arris." These channels are always twenty in number, and are so placed that one is always seen in the center of the column on each of its four faces.
51. To draw a column with channels, it is necessary to make a plan just above the base, that is to say, at its greatest diameter, and another at its smallest diameter or at the necking cf the column. (Plate TTT.) Having divided the semi-circumference into twenty different, parts, and having determined the radius through each point of division, draw a chord of the arc comprising tWo of these divisions; and with an opening of the compass equal to one-half of this chord, and from the point where it inter sects the radius which divides it into two parts, draw a semi circle outside of the circumference of the column. The summit of this semi-circle will be the center of the arc of the circle that forms the channel. By taking the corresponding point on each alternate radius all the channels may be drawn with the same opening of the compass. As a result of this method, the arc of the Doric channel is exactly a quarter circle.
52. The head or upper part of each -channel is a semi circle, while the foot rests on a plane inclined at forty-five degrees. In drawing a channeled column there is but one channel seen in direct front elevation, the others follow the curvature of the shaft, and are drawn according to their positions on the plan. They form at the upper and lower extremities different curves which can be obtained only by projecting the proper points.
Thus, to obtain the curves formed by the heads of the channels draw (in elevation) the semi-circle forming the head of the central channel, and divide the plan of each one into eight equal parts. Now project upward the points of division on the plan of this cen tral channel by vertical lines drawn to intersect the semi-circle in elevation. From these points of intersection, draw horizontals which will pass tl rough all the other channels. Then draw verticals
from the plan of each channel, as has already been done with the central one, and -at the intersection of these verticals with the respective horizontal lines, points of projection may be marked by means of which one may describe the various curves.
For the foot of the channels the section must be used to estab lish the points of projection by dividing the inclined plane into three equal parts, and from each of these points of division, hori zontals passing through all the channels may be drawn; then, dividing the depth of the channel on the plan into three equal parts, one may draw from the center of the column, two circles passing through all the channels. At the points where these circles inter sect the outlines of the several channels, points are found in plan which may be projected to the horizontals of the elevation. Through these points may be drawn the several curves of the channel footings.
53. This plate shows also the details of the capitals and bases of the two Doric Orders. The left half shows the Denticular and the right half the Alutular. Order. The capitals have the general characteristics' of the Tuscan capital, but they have several differences of detail. For example, the abacus is enriched by a small cyma-reversa with a listel or fillet; while the necking is separated from the quarter-round by three "annulets" in the denticular, and by an astragal in the mutular order.
The height of the Doric capital is the same as that of the Tuscan Order, twenty-six, divided thus: the necking eight, the annulets or astragal three, the quarter-round five, the abacus six, the cyma-reversa two, and the listel two; the total projection of these members is ten, of which two is the projection of the cyma reversa, .5 is the projection of the abacus beyond the quarter-round, five for the quarter-round in the (lenticular order, and 2.5 for the three annulets The quarter-round in the mutular order is of the same height as In the denticular but it has a projection of six, and is drawn with a radius of six, and the conge of the astragal has a projection of one and five-tenths. The shaft of the column terminates below the necking of the capital by an astragal of three parts, of which one is for the annulet, and two for the bead or ring; the conge has a • projection of one.