The water for the baths was heated in brick furnaces, consisting of two rows of cells arranged over the fire, with which the lower row was in contact, while the upper row received the water from the branch of the aqueduct furnishing the supply. Pipes from the lower cells led into the baths, and these pipes were surrounded by flues, in order that the water should not cool in its transit. The party-walls between the cells of the furnace were also traversed by flues, in order to economize fuel as much as possible. Private baths, on a smaller scale, were attached to every house of consequence; and were favorite places for the display of the owner’s wealth. The theatres of both nations were constructed with great skill, and especial adaptation to the ends of sight and hearing. They were generally built on the side of a hill, and sometimes, in Greece, literally hewn out of the solid rock. Some were of vast size; the ruins of one at Argos, semi-circular in form, inclose an area 450 feet in diameter. The seats for spectators were arranged in ascending stages, and the outer wall of the structure, behind the topmost row of spectators, was surmounted by a kind of portico, in order to throw back the sound of the actor’s voice. The semi-circular included space was the “orchestra,” where the chorus danced on a boarded floor. The stage, of course, closed the opening of the semi-circle, and was approached from the orchestra by steps. The back of the stage was bounded by a lofty screen, which in the theatre built of wood during the ædileship of M. Æmil. Scaurus was composed of three different substances--the bottom of white marble, the centre of glass, and the highest of gilt wood. The early theatres of Rome were built of wood, but after the time of Pompey stone was universally employed. The art of scene-painting was well understood, and various machines were employed on the stage for instantly changing the scene, or for introducing the actors flying in mid-air.