This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol6", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
Theatres are perhaps the most difficult of all buildings that an architect is ever called upon to plan. A considerable knowledge of stage craft is above all things necessary, for there is not only the auditorium to arrange, so that everyone shall be able to see and to hear, and with entrances and exits so contrived that there shall be no crushing, and that the theatre may be emptied in case of emergency with extreme rapidity; but there is behind the scenes a large and practically a separate building, which must have a large space devoted to scenery and the necessary machinery for shifting it, together with dressing-rooms for numerous performers. It is now considered essential that a theatre should be detached from all other buildings, at least on three of its sides, while it is much better if it is entirely isolated; as the risk of fire is considerable, and has to be guarded against not only within the building itself but outside also, in order that, if a fire arises, it shall not be communicated farther; while isolation also permits of the fire engines and escape ladders being brought to all parts. The risks of fire and of panic have proved to be of so serious a nature that everything possible is done to minimise them, the modern theatre being constructed almost entirely of fire - resisting materials, such as brickwork, steel, and concrete, even the hangings and upholstery being saturated with a substance which renders them non-flammable. It is also customary to separate the stage from the auditorium by a fire-proof curtain, down which a stream of water can be made to pour by merely opening a tap, so that if a fire originates in either of the great sections of the building it should not be communicated to the other, there being no direct means by which the one can be reached from the other, except perhaps below the stage level. Water sprinklers, to which attention has been called in an earlier volume of this book, are usually fitted in several parts of the building, particularly in what are known as the "flies" and on the "grill" above the stage; for it is always necessary to carry up this part. of the building to a great height for the accommodation of lifting scenes. Artificial lighting has also to be considered in the planning, though as a rule this is now done by electricity and is a comparatively easy matter to arrange. Still, there should always be two sources of light, so that in the event of an accident happening to the electric wires the house may not be left in utter darkness, but an alternative method of lighting, such as that by means of gas, should be immediately available.
In many theatres oil lamps are also kept in store, but these must be of the colza oil pattern, burning heavy oils, the highly inflammable mineral oils being inadmissible. The greatest danger of fire exists in the use of naked gas lights, in order to produce special effects upon the stage, in close proximity to flimsy curtains and oil-painted canvas, the head-lights and foot-lights which are in view of the audience causing comparatively little danger. It is now usual for all these to be electric, but additional gas burners are generally provided along the front of the stage, or proscenium opening, as it is called, both at top and bottom, and occasionally standards of gas burners are still to be found in the wings, though careful managers avoid them.
Possibly an understanding of the general principles of theatre planning will be best obtained by considering one well-designed example, and that of the Garrick Theatre, planned by Mr. Walter Emden, has been selected, as, although small, it illustrates all the principal points (see Fig. 6). It is placed on an awkwardly shaped piece of land, but is so contrived as to be almost entirely isolated, the only portion which adjoins other buildings being at the back of the stage, where it is cut off from all else by a thick brick wall. The dressing-rooms occur in a detached building, which communicates with the main building only by a subway, this rare arrangement being rendered possible by the peculiar shape of the land, whose awkwardness was thus very cleverly brought into use. Thus in this case the theatre consists of three distinct buildings, - the auditorium, the stage, and the dressing-rooms, which may very well be considered separately.
The principal floor is that at the boxes level, the plan being followed, which is now very common, of sinking the pit, the stage, and its cellar in a huge excavation below the ground, it having been found that by this means exit is rendered more rapid, while the introduction of scenery from without is made easy, and in case of panic or fire access can readily be obtained to all the parts. It will be noticed, on reference to the plan, that the theatre is arranged longitudinally along a straight frontage to Charing Cross Road, from which there are several entrances. The main entrance serves through the grand vestibule to the stalls by means of staircases which pass downwards, and to the boxes at the level of the back row; while, although there is a separate door for the upper boxes, the staircase leading to them also communicates with the main entrance, so that the same box office serves for the boxes and stalls. The stairs require a good deal of careful investigation, as they are planned so as to overlie one another, this being a common feature in theatre work; for it is essential that each part of the house may be reached independently, and shall have exits quite separate from one another, and from all else, leading to two different streets or sides of the building at least. Thus the boxes are reached, as has just been said, through the main entrance and the grand vestibule, but they have an emergency exit on the same level to the back lane. The stalls have two stairways down to them from the vestibule, and as this is large there is no necessity for giving a further emergency exit, though it could be obtained by climbing over the barrier between the stalls and the pit, shown on the plan at pit level. The upper boxes are reached from the main entrance, up quite a short flight of stairs which passes up beneath the lavatory shown on the front of the plan at the upper boxes level, while an emergency exit is found at the back beside the bar, for which, like the other stairs, a single straight flight suffices. There is an entrance for royalty, marked with a crown, in the middle of the principal frontage, yet set back so as to secure a certain amount of privacy. A private room is reached through a porch, whence the private boxes can be reached at the boxes level by passing down a few stairs; for it may be noticed that when we speak of the boxes level we do not necessarily mean a horizontal plane, as the seats on each of the "levels" are necessarily arranged in tiers, so that the persons seated in the back rows may see over the heads of those in front. In case of emergency royalty can escape through their private room or else by any of the other means of escape from the boxes.