The Worcester spy. [volume] (Worcester, Mass.) 1898-1904, 1901-11-24
mo NECESSITY FOR
THEATRE .DRAUGHTS

A Solution Of the Problem Of Sup
plying Pure Air to Large Au-
dienCes--VentiIatiOn Tested by
Lighted Candles-ExperimentS
With Churches Show Equally
Good Results
Boston. Nov 90, 19O1.-Professor S.
Homer Woodbridge, of the Massachu-
sets Institute of Technology, who has
recently had charge of the improve
ment of the ventilation of the Capitol
at Washington, has prepared a general
statement of the problem of properly
lventilating theatres, churches, and au-
dience halls which is of very general
interest since, although the buildings
in which he has made his experiments
are mainly here in Boston, yet the con-
ditions in this city are practically du-
plicated, to a greater or less extent
according to size, in every other city in
the country,
The Importance of the subject will
be realized by any one who has sat in
crowded auditorium, coming in from
the fresh air out of doors only to go
home, however entertaining the per
Torrance of eloquent the speaker, with
a headache or sensation Of heaVlness
arising from the impure air, or with
cold, or worse from the draftiness
caused by an unscientifjc method of
ventilation. Professor Woodbridge
points out that in residences, Offices
shops, and the like the air space to
each occupant varies from 5000 cubic
feet. say, down to 500; while in audito-
RUINS the individual space is only 500
as a maximum and often sinks to as
low as so. In the auditorium, there
fore, special methods of ventilation are
an absolute necessity, but the sort of
ventilation that the contractor or ar
chitect provides is often as dangerous
one may almost say, as no ventilation
at all.
Yet the principles on which correct
ventilation depends, although 80 sell
dom fully recognized, are simple
enough when once stated. For exam
pie, it is obvious that the smaller the
space through which volume of ven
tilating air is to move, the more rapid
its motion must become--w ac-
counts for one of the more important
difficulties of auditorium ventilation.
And the movement of Ventilating air
becomes sensible. it is obvious again,
in a ratio corresponding with its velo-
city or with the drop in temperature
which it causes or with both.
Obviously, too, the aim of the ventl-
lating engineer should be to furnish
maximum in the air quantity with
minimum in draft effect. Usually he has
gone about his task by what appeared,
on first examination of the problem to
be the easiest and simplest way, though
in the end either wholly or partly inef-
fective That is, he has introduced his
fresh air at the ceiling of the audito-
rum, as being removed farthest from
his audience, his flow or air extending
thence downward, in an area which
might be likened in shape to huge
tent covering the floor of the theatre
or audience hall, the overplus of air
escaping, that is, at vents S catered
equally over sthe floor.
The method looks reasonable enough
at first, but it is essentially faulty.
For instance, it ignores the influence
of the audience itself, each member
lighted candle, contributing to heat the
surrounding air. Thus Prof. Wood
bridge states that if through theatre
seating 2500, 10000 cubic feet of air an
hour are passed. the ultimate rise of
temperature from this aggregate hu-
man heat may be safely estimated as
III or II degrees Fahrenheit. 1t is clear
enough, then thCt the cooler air enter
ing at the top of the theatre,
with the humanity overheated air
at the bottom of the room will
create a state of unstable equi-
librium, and that by an immu-
table law the cooler air at the top
must fall while the warmer and lighter
air at the bottom must rise. The re-
suit will be drafts, fitful or steady as
the case may be. And the higher the
ceiling-the place, that is, which has
been selected as being most remote
from the audience and therefore the
most unlikely to produce drafts-the
more violent these drafts will be. The
remedy is to reduce the air quantity
in itself a confession of weakness, or
to increase the temperature of the air
supplied, which is much the same
thing.
1t is further pointed out that cur
rents of unequally heated air are not
only unhygienic, but that they serious
ly interfere with the transmission of
sound from the stage or platform, the
finer qualities of the singers or speak
er's voice being often quite lost as a
result Even more important is the
question of air impurity Not only
does each member of the audience in
fluence the temperature, but he takes
to himself a proportion of the vital
properties of the air, and returns to
it his own semi-poisonous eXhalations;
besides throwing off a certain amount
of what Prof Woodbridge aptly calls
personal debris" With the imperfect
method of downward ventilation" as
it is called, just described, it will be
seen that a large part of these noxious
eIements-which in the main cause the
greater part of the immediate dis
comfort to an audience in an illventila-
ted room-connot be eliminated from
the atmosphere Immediately surround
ing the breather
BY substituting upward ventilation,
so called, for downward, however. it is
evident that the amount of fresh air
needed to maintain a definite standard
of purity would. in the first place, be
much less. Prof. Woodbridge, for eX-
ample gives the following illustration
! in which the candles of course repre-
sent the human audience: An other
wise tight small chamber has been
fitted with a perforated floor and cell
ing: candles have been closely placed
upon the floor and lighted, and the
chamber has been furnished with just
enough air through the floor to bring
and keep the candle flames at fun
/ brilliancy. When this same air guam
/ tity was supplied through the perfor-
ated ceiling, the flames dwindled al
most to the point of extinguishment,
/ the candles were smothered and soft
ened, dropped. and bent double in their
/ own vitiated air and heat brought
( back upon them by the downward