Another method of doing this, without marking the drawing, is to make a scale A II, with the proportional compass in the same manner as marking the distances from the centre, viz. having set the proportional com pass as before, make 0.1, No. 2, equal to OA, No. 1 ; and make 0 b equal to the distance of the shorter ends. Take 06 with the longer ends, and mark the distance O c with the shorter ends. Again, take 0 c with the longer ends, and mark 0 d with the shorter ends. Pro ceed in this manner through the whole eight points, which are the number in a revolution. Draw 0 13 of any length, making any angle with OA ; draw AB, b B, c 11, d 11, Re. Take the successive distances OA, 0 b, 0 c, 0 d, Sec. upon the edge of an ivory rule or straight slip of paper, and apply them in No. 1. from 0 to A, from 0 to II, flow 0 to C, &c. to I, marking the points A, 11, C, D, Re. In No. 2, draw i E parallel to 011, cut ting All at E ; draw El' parallel to AO, cutting i B at G ; draw Gli parallel to 011, cutting OB at II ; and drat% Ill parallel to AU. Then EF will be a scale to set off the second revolution in the same manner as the first ; and in like manner III will be a scale for the third By this means, and from the same scale, the whole number of intermediate spirals may be drawn with out pricking the paper, marking the points with a sharp pencil instead of a steel point.
To describe the proportional spiral with a compass, the same data being given as before; Fig. 3.
Let the point C be ascertained as before. Join ABC, which bisect by a perpendicular IlD ; make BD equal to BA or BC; draw DA and DI1C, and the diagonal DM' ; at right angles thereto draw IIOJ. Draw FIFE parallel to AD, FUG parallel to DIIC ; proceed towards the centre with every succeeding point in the same man ner ; and D, I I, F, J, &c. will be the centres. From I), with the distance DA, describe the quadrantal arc AC ; from II, with the distance 1IC, describe the quadrantal arc CE ; from 11, with the distance 11E, describe the quadrantal arc EG ; proceed in this manner until as ma ny quadrants arc described as that the last will meet the rye of the volute, and this will complete one of the spi rals. Suppose again it were required to draw another of the interior spirals through the point M in the cathe tus 0.1; draw MN parallel to AC, cutting OC at N, then N will be the next point in the quadrant ; proceed to find all the succeeding quadrants of this spiral as be fore, and thus the volute may be completed.
The general proportions of the Ionic order for prac tice, is as follows, (Plate CL1X. Fig. I.) Divide the whole height into twenty-one equal parts ; give four to the height of the entablature. Divide the height of the entablature, Fig. 2. into three equal parts ; make the cor
I ice, frieze, and architrave, each one part : divide the height of the architrave into four equal parts; give one .o the mouldings of the uppei part or capital : divide the ,,apital of the architrave into nine equal parts ; git e one to the upper fillet, three to the cavetto, four to the ovolo, and one to the beach : divide the height of the biezetnto nix equal parts; and give the upper one to its capital : ide the height of the cornice into three equal parts: divide the upper part into six parts, give one to the up per fillet, four to the cima-recta, and one to the lower fillet, and turn one downwards for the ovolo under ; divide the lower third of the cornice into six equal parts, and dispose of the parts as appears by the scale. The height of the base, including the plinth, is half the diameter; the parts are proportioned in height as appears by the scale. The whole height of the capital is three-fourths of the upper diameter ; the height of the volute 7-I2ths of the lower diameter. Dividing the height of the vo lute into three equal parts, the top of the lower one reaches to the bottom of the ovolo, the second division upon the top of the festoon : the smaller members will be found by subdivision. The juttings of the members are as follows: the cornice projects equal to its height ; the projections of the intermediate members will appear sufficiently clear by the horizontal scales affixed to the Plate The general projection of the base is one-sixth of the lower diameter of the column.
The entablature is principally imitated from the ele gant example of the temple of Minerva Polins at Priem, and the capital from the Ionic temple on the Ilvssus at Athens, which is one of the boldest examples, and marks the character of the order in the most decided nraimer.
Of the Corinthian Order.
Unless we admit the account given by Vitruvius re specting the intention of the capital by Callimachus, who is said to have been an Athenian sculptor, and a contem porary of Phidias about 510 13. C. there is no certain et idence with regard to the time when this order was established. Pausanias (hook viii.) says, that in the fourth century before the Christian era, it was introduc ed by Scopas in the upper range of columns in the an cient temple of Minerva at Tegea ; but it has been al hedged, that there is a strong probability that this temple was only begun by Scopas, but being left unfinished, had this upper range added, upon the lower ancient Doric, under Homan influence. There must certainly have been some particular reason why this order was called Corin thian ; but Doric remains only have been discovered on the site of that city by modern visitors.