The age-herald., 1901-11-24
No Necessity for Theatre Draughts.

Boston, November 23.-Prof. S. Homer Woodbridge of the Massachusetts Insti- tute of Technology, who has recently had charge of the improvement of the ventil- ation of the capitol at Washington, has prepared a general statement of the problem of properly ventilating theaters, churches and audience halls which is of very general interest, since, although the building in which he has made his exper- iments are mainly here in Boston, yet the conditions in this city are practically duplicated, to greater or less extent ac- cording 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 from the fresh air out of doors only to go home, however entertaining the performance or eloquent the speaker; with headache or sensation of heaviness arising from the impure air, or with a cold, or worse, from the draftiness caused by an unsci- entific 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
 
 riums the individual space is only 800 as a maximum as often sinks to as low as 50. In the auditorium, therefore, spe- cial methods of ventilation are an abso- lute necessity, but the sort of ventilation that the contractor or archit ect provides is often as dangerous, one may almost say, as no ventilation at all.
 Yet the principles on which correct ventilation depends, although so seldom fully recognized, are simple enough when once stated. For example, it ss obvious that the smaller the space through which volume of ventilating air is to move the move rapid its motion must become which accounts for one of the more inn portant difficulties of auditorium ventila- ton. And the movement of ventilating air becomes sensible. it Is obvious again, in ratio corresponding with it's velocity or with the drop in temperature which it causes, or with both.
 Obviously, too. the aim of the ventil- ating engineer should be to furnish a maximum in the air quantity with a min mum 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 ineffec- tive. That is, he has introduced his fresh air at the ceiling of the auditorium as being removed farthest from his audi ence, ms HOW or air extending thence downward, in an area which might be likened in shape to a huge tent covering tho floor of the theater or audience hall, the overplus of air escaping. that is, at vents scattered equally over the floor.
 The method looks reasonable enough at first, but 1t is essentially faulty. For in- stance, 1t ignores the influence of the au- dience itself. each member of which may be compared to big lighted candle con- tributing to heat the surrounding air. Thus Professor Woodbridge states that if through a theater seating 2500, 4000 cubic feet of air an hour is passed, the ultimate rise of temperature from this aggregate human heat may be safely es- timated at Il or 12 degrees Fahrenheit. It Is clear enough. then, that the cooler air entering at the top of the theater. with the humanly overloaded air at the bottom of the room, will create state of unstable equilibrium, and that by an i'm nut table law the cooler air at the top must fall while the warmer and lighter air at the bottom must rise. The result 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 the most remote from the audi ence 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