With the incline of the main floor established, experimental sectional lines to determine the balcony slope and the various sight lines should be drawn on the section of the plans, as follows:

From a point corresponding to the position of the eye of a person seated in the last row of seats (about three feet above the floor level) draw a vision line underneath the balcony to the top of the proscenium opening. This vision line fixes the lowest possible vertical position of the underside of the balcony.

Balcony Risers

A line drawn from the base of the stage at the intersection of the curtain line and main floor level through the top of the first riser to the top of the rear balcony riser will determine the various heights of intermediate risers.

Then draw two vision lines from the eye points of persons seated in the first and last rows of the balcony (about three feet above the floor level) to a common point well below the front line of the stage. This will establish the balcony sight lines.

Sight-Lines With Wide Balconies

If the balcony be a wide one with curved sides, additional sight lines should be drawn on both sides, and from underneath the balcony on each side as well, to fix the sight lines at these points. These additional lines may make it necessary to lower the balcony sides a trifle with a downward curve.

Stairways

Should the sight lines not prove satisfactory, a minor change in the slope of the main floor or the elimination of a single row of seats from the balcony will cause a considerable improvement. The correct pitch for a balcony should never be over fifteen and a half inches for each riser, or two steps of seven and three-fourths inches each.

In designing stairways leading to balconies due regard must be given to employing the fewest possible number of steps, and where possible, the steps should be arranged between landing platforms in groups of not more than a dozen continuous steps. If the balcony be a high one, there should be an intermediate mezzanine floor, with a broken pair of stairs on each side of the house, and continuous broken flights extending from this floor to the rear level of the balcony, The principal stairways from the different parts of the house should lead direct to the foyer or lobby, with runs that turn in one direction only. For an example of ingenious stairways see illustration at the end of this chapter.

Balcony Entrance Tunnels

From the mezzanine floor, pierce the balcony with entrance tunnels on each side of the house to the cross passage in the rear of the front tier of balcony loggias. If the balcony be very wide construct in addition intermediate tunnels. Cloakrooms and administration offices may also be placed on this mezzanine floor, which should be cut out and designed like a balcony for the foyer below.

The Cantilever Principle

There should be no exposed posts to hold up the balcony. It should be supported on the cantilever principle, either with or without cross trusses resting on columns imbedded in the walls. Sometimes it is possible to inclose a series of two-inch or three-inch Lally columns in the partitions between the boxes as additional support.

The seating conditions will be discussed separately in the chapter devoted to "Comfort."

Orchestra Well

It is highly important that the lines encompassing the orchestra well should be so arranged as to insure good acoustics and at the same time conceal all view of the musicians from the audience. There is nothing more disturbing in a theatre than the heads of musicians bobbing into view above the orchestra rail during a performance. Soft strains of hidden music will give the effect of coming from a distance, and are far preferable to the blatant blasts of an exposed brass band.

It is also of advantage to have a suitable sound-space underneath the orchestra well, and, if possible, surrounding it. The Court Theatre at Wiesbaden, Germany, has an arrangement whereby divisional platform sections of the orchestra well are mounted on hydraulic lifts, which may be elevated to suitable heights or even to the level of the auditorium floor if desired.

The orchestra well of the famous Wagner Opera House at Bayreuth, a diagram of which is shown on Page 133, embodies an excellent arrangement for an orchestra well. Supplemented with hydraulic lifts and a sounding space, such an orchestra well would be ideal.