. But when entrance and egress are
constant, or required by crowds, certain further modifications must take
place.

[Illustration: Fig. XLIII.]

Sec. IV. When entrance and egress are constant, it may be supposed that
the valves will be absent or unfastened,--that people will be passing more
quickly than when the entrance and egress are unfrequent, and that the
square angles of the wall will be inconvenient to such quick passers
through. It is evident, therefore, that what would be done in time, for
themselves, by the passing multitude, should be done for them at once by
the architect; and that these angles, which would be worn away by
friction, should at once be bevelled off, or, as it is called, splayed,
and the most contracted part of the aperture made as short as possible,
so that the plan of the entrance should become as at _a_, Fig. XLIII.

Sec. V. Farther. As persons on the outside may often approach the door or
depart from it, _beside_ the building, so as to turn aside as they enter
or leave the door, and therefore touch its jamb, but, on the inside,
will in almost every case approach the door, or depart from it in the
direct line of the entrance (people generally walking _forward_ when
they enter a hall, court, or chamber of any kind, and being forced to do
so when they enter a passage), it is evident that the bevelling may be
very slight on the inside, but should be large on the outside, so that
the plan of the aperture should become as at _b_, Fig. XLIII. Farther,
as the bevelled wall cannot conveniently carry an unbevelled arch, the
door arch must be bevelled also, and the aperture, seen from the
outside, will have somewhat the aspect of a small cavern diminishing
towards the interior.

Sec. VI. If, however, beside frequent entrance, entrance is required for
multitudes at the same time, the size of the aperture either must be
increased, or other apertures must be introduced. It may, in some
buildings, be optional with the architect whether he shall give many
small doors, or few large ones; and in some, as theatres, amphitheatres,
and other places where the crowd are apt to be impatient, many doors are
by far the best arrangement of the two. Often, however, the purposes of
the building, as when it is to be entered by processions, or where the
crowd most usually enter in one direction, require the large single
entrance; and (for here again the aesthetic and structural laws cannot be
separated) the expressio