In the 18th century, David Garrick, an actor, manager and playwright, restructured the stage so that the audience remained completely separate from it. The actors kept their actions to the area behind the proscenium, the section of the theater between the curtain and the orchestra. Most European theaters restricted the action of the play exclusively to this area, but some English theaters also used an extended forestage or apron. Two doors on the proscenium separated the apron from the rest of the stage, and for the first half of the century, most acting in English theater actually took place on the forestage.
In order to make scenes appear more vivid, the architect Giovanni Battista Aleotti designed a theater with a permanent arch meant to frame the scenery. Additionally, to give added depth and perspective to the scenery, designers began painting scenery on parallel wings that receded from the audience. These flat wings also made changing scenery easier. The wings for later settings rested just behind the wings for the present setting. When the scenery needed changing, the stagehands simply removed the front wings and placed them at the rear.
By the early 17th century, theaters already used footlights and sidelights to better illuminate the actions of the actors on a dark stage, thanks to the innovation of the architect Joseph Furstenbach. From the beginning and well into the 18th century, these lights mostly consisted of candles. In 1783, a kerosene lamp with an adjustable wick took dominance over simple candlelight. By 1791, William Murdock, a Scottish inventor, devised a way for theater buildings to use illuminating gas in quantity. Since this required constant attention, however, kerosene lamps still maintained their status as the lighting instrument of choice.
The overall structure of the theater and stage area contributed to the effect and efficiency of acoustics. Enclosed theaters with oval and ellipsoidal building designs competed with one another to determine which layout aided the acoustics best. Moreover, the arch separating the proscenium from the audience helped prevent audience noise from muffling out the lines of the actors, and arched ceilings above the stage further amplified the noises of the play.