All that has been said hitherto concerning theatres refers chiefly to their planning and general arrangement as far as they affect life. The actual construction has not yet been discussed. As far as it affects the safety of the people, the construction need only be such that it will successfully resist fire for a period sufficiently long to enable the people to make their escape. Wood is not entirely objectionable as long as it is used in heavy pieces with close joints, and an absence of sharp corners and exposed edges, on what is known as the " Slow burning principle." Solid wood stairs are probably less liable to cause slipping than are those of stone, while firemen often prefer them to those of incombustible construction, as they will support a load until they are almost burnt through, while those of stone may suddenly give way without warning.

As far as the protection of property is concerned, the principles discussed in Volume IV.with reference to other buildings apply equally here, while especial care should be taken to see that the effort to gain all possible space and uninterrupted view is not carried to the extent of leaving the metal work insufficiently protected.