Exhibitor's Trade Review (May-Aug 1925)

Page 56 Exhibitors Trade Rsvimv Th Why and Wherefore" of Theatre Ventilation VENTILATION consists of the removal of the products of respiration and the various odors incidental to an auditorium by replacement of the contaminated air content at a continuous rate proportionate to the size of the audience. Natural ventilation is not satisfactory, and ventilation by mechanical means is divided into two classifications. In one group are those systems in which air is withdrawn from the auditorium, and in the other the system of forcing air into the audience chamber, thereby displacing the vitiated air, which escapes fortuitously or through ducts. There is also a combination of the displacement system with the withdrawal system, and the air is caused to move through a closed circuit in and out of the auditorium. SUMMER "COMFORT" FOR PATRONS It might be said that the primary purpose of ventilation is physical comfort and not the removal of carbonic-acid gas. As a matter of fact, the proportion of this gas in an auditorium is far below the limiting quantity beyond which discomfort and poisoning takes place. The chief cause of discomfort in an "illventilated" theatre is not in this product of respiration but in the non-removal of body warmth and vapors of perspiration by the immobility of the air. If such air is agitated and kept in motion, it is much more "breathable," so far as the physical sensations of the audience are concerned. The convection effect of warmed air causes it to rise to the ce ling of the auditorium, and to make the gallery stifling hot. This can only partly be combated by means of small electric fans, which have the disadvantage of creating a too intense disturbance in certain localities and of being utterly inactive in corners. In the spoken drama, the use of these fans is practically out of the question, owing to their noise. MODERN VENTILATING PRACTICE The desired result may be secured, however, by taking advantage of the fact that where a displacement supply of air is forced into an auditorium and a duct system withdrawing air is installed elsewhere in the auditorium, the moving air current tends to short-circuit from the pressure grating in a direct line to the vacuum gratings. Now, if these two gratings or sets of gratings are carefully placed with regard to each other, they will create an air current which can be directed to sweep across the audience in the orchestra and galleries, placing the patrons of the theatre in a gentle, constantly renewed stream of air, and leaving unchanged the large mass of air in the upper spaces of the auditorium, in front of the galleries and above the orchestra seats, and which requires no renewal. As people are extremely sensitive to the least draft coming from behind, this air stream is invariably directed from the stage to the rear of the audience. A large mass of unmoved air absorbs or (Continued on following page) $25-00 PER YEAR GIVES YOU ABSOLUTE PROTECTION AGAINST FIRE IN YOUR THEATRE A Marvelous New Device Send for Full Information The CLEVELAND Film Protector Corp. 811 Prospect Ave. CLEVELAND, O. ZSPhelco!" CharlesW.Pheffis&Co. INCORPORATED J 30 West 42nd Street, New York Iran^rteK says "I'm going to tell you why you need me" The Public demands Good Pictures and that they be presented without strain to the eyes. Put me on the job and watch the flicker and fluctuation disappear. I change your alternating current into direct current with four to five times the candle power of an alternating current arc of the same amperage. To really know how much "Transverter" can do for you just write for one of our folders. It will interest you. Send for it today. I make it easy for you to perfectly dissolve your pictures and make your projection more artistic in many ways. c^HERTNER ELECTRIC COMPANY "Ljocxxst Avenue Cleveland , OHio U S A.