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HISTORY OF ENGINEERING.

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imitated down to the present time, in all buildings erected for that purpose. 'The examplesat Pisa show how admirably adapted it was for the Catholic worship, and the Norman andSaxon ecclesiastics continued to make use of such models for whatever new erections theyundertook.

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Fig. 123.

BASILICA AT PANO.

The basilica, which adjoined the forum, in the Augustine age, was of the greatestimportance: whatever was imposing in architecture was applied to it. The forum, gracedwith porticoes, statues, temples, triumphal arches, was by the citizens made their commonplace of resort, to which in time were added libraries and places of amusement.

Of the Theatre. The extent of some of the theatres which remain, and the manner of con-structing them, deserve some attention, as they were first cut out of the sides of a hill, theproscenium being added to suit the locality, which required great skill on the part of theengineers who excavated them. In the early examples, the seats were cut out of the solidrock, and, from the convenience they afforded for the assembly of numbers, were often usedfor other purposes than the drama. The seats, elevated one above the other, affordedthe spectators an opportunity of viewing the country, which rendered it necessary in aftertimes to limit their vision to the theatrical representations, when the whole was inclosedwithin a lofty wall. Vitruvius tells us how these buildings were set out: —within a circlewas inscribed three squares, the angles of which were to touch the circumference; thatsquare, the side of which was nearest the scene, and which cuts off a segment of the circle,marked out the extent of the proscenium, and another line drawn parallel to this last, andforming a tangent to the circle, determined the front of the scene. Through the centre aline was drawn parallel, which separated the pulpitum of the proscenium from the orchestraIn the orchestra the seats for the senators were placed, and the other portions of the theatrewere so divided, that the angles of the triangles, which touched the circumference, pointedto the directions of the ascents, and steps between the eunei, on the first precinctories orstories. Above these the seats were placed, which formed the upper cunei, in the middle ofthose below. The angles pointing to the staircases were seven in number, the remainingfive, marked the points of the scene; that in the middle, the royal entrance ; those on theright and left, for the attendants. Hie seats on which the spectators sat were not lessthan 20 inches, or more than 22 inches in height, and their width from 24 to 30 inches.All the spectators were so situated, that they sa%v equally well, and the voice of the actorwas heard by all. The seats were so arranged, that a cord draw’n from the lowest to thehighest touched the edge of each; and at the top a covered portico sheltered the spectatorsduring the intervals of the drama from the heat of the sun.

'The Proscenium was adorned, towards the theatre, with columns, niches, and statues ;the stage was formed of wood ; beneath which were various machines for adapting thescenes, and imitating thunder. Painted scenes, and triangular slips, which could beturned round, with devices upon them, and a quantity of machinery of various kinds, wereintroduced, to heighten the effect of the representations.

The top of the scene was level with the roof of the portico, so that the voice was distinctlyconveyed to those on the upper seats.

Rehind the scenes were porticoes, which, in case of sudden showers, might be resorted to,which communicated with verdant and pleasant walks, dug out and drained to the lowestpossible level; to the right and left, sewers were constructed, which served for this purpose,llie walks were carefully formed, taking out the earth to a certain depth : the space wasfilled with charcoal, on which a layer of gravel was spread, and Vitruvius tells us that in atime of siege, these walks were sometimes opened, and the charcoal taken out, and dividedamong the inhabitants . thus they contributed to health during peace, and preservation in thetime of war.