There were three entries in front, and two on the sides; the middle entry (termed the Royal door) was always that of the principal actor; thus, in tragedy, it was commonly the gate of a palace. Those on the right and left were destined to the second-part players, and the two others, on the sides, one to people from the country, the other to those from the harbour, or any public place.
Pollux informs us, that there were trap-doors for ghosts, furies, and the infernal deities. Some under the doors, on one side, introduced the rural deities, and on the other the marine. The ascents or descents were managed by cords, wheels, and counter-weights. Of these machines none were more common than those which descended from heaven in the end of the play, in which the gods came to extricate the poet in the _denouement_. The kinds were chiefly three; some conveyed the performer across the theatre in the air; by others, the gods descended on the stage; and a third contrivance, elevated, or supported in the air, persons who seemed to fly, from which accidents often happened. (It is from this that the well-known phrase "_Deus ex machina_" has its origin.) As the ancient theatres were larger than ours, and unroofed, there was no wheel-work aloft, but the performer was elevated by a sort of crane, of which the beam was above the stage; and turning upon itself, whilst the counter-weight made the actor descend or ascend, caused him to describe curves, jointly composed of the circular motion of the crane, and the vertical ascent. The _anapesmata_ were cords for the sudden appearance of furies, when fastened to the lowest steps; and to the ascension of rivers, when attached to the stage. The _ceraunoscopium_ was a kind of moveable tower, whence Jupiter darted lightning, supposed to be the Greek fire, as in Ajax Oielus. The machine for thunder (_bronton_) was a brazen vase, concealed under the stage, in which they rolled stones. Festus calls it the Claudian thunder, from Claudius Pulcher, the inventor. The most dreadful machines were, however, the _pegmata_ (a general term also for all the machines), which first consisted of scaffolds in stories, &c. These first exhibited criminals fighting at the top, and then, dropping to pieces, precipitated them to the lower story, to be torn to pieces by wild beasts. Sometimes they were for vomiting flames, &c. The _theologium_ was a place more elevated than the stage, where the gods stood and spoke, and the machines which held them rested.