, Mechanical Science, ' 469 



and havinp^ nothing as a protection but the powerful current of air 

 which passed throuj^h the theatre, and proceeded to invigorate the 

 combustion of the scenery and wood- work upon the stage. Nearly 

 the whole of that part of the theatre was on fire, but the public 

 portion quite untouched, when a piece of inflamed wood fell on the 

 left side of the centre, rebounded over the balustrade, fell into the 

 orchestra, and then set fire to one of the benches in the pit. The 

 combustion of that part thus commenced, but the current of air 

 towards the stage was so rapid, that the smoke passed nearly hori- 

 zontally towards it, and the fire made but slow progress in the pit. 

 I witnessed this effect for more than half an hour, and beheld the 

 orchestra, and nearly the whole of the pit in flames, without there 

 being any sensible portion of smoke in the body of the theatre 

 above the first tier of boxes. I was then obliged to work at a pump, 

 and prevented from observing any longer the progress of the fire." 

 M. D'Arcet then observes that an impermeable metallic screen 

 would, in any such case, have done far more harm than good. 

 Supposing it strong enough to withstand the pressure of the air 

 upon it, it would quickly become red-hot, and from causing the 

 ascent of a current of highly-heated air on its side towards the 

 t)ody of the theatre, would, in every way, tend to inflame that part 

 of the building ; it would also confine the air there, and in a few 

 moments make it unfit for respiration. On the contrary, an open 

 metallic screen, with large meshes, would appear to present great 

 advantage; the aif woyld pass freely, and consequently, exert no 

 serious degree of pressure upon it; the screen itself would be 

 preserved cool by the rapid current going through it : inflamed 

 pieces of wood, when falling, would be retained on the side already 

 in flames ; the firemen could throw water through it upon the 

 burning places on the opposite side, and none of the inconveni- 

 ences would be occasioned by it, which so evidently belong to the 

 impermeable screen. 



In Paris, the architect is obliged, by law, to construct a thick 

 wall across the theatre, between the audience part and the stage 

 with all behind or belonging to it. The following are the directions 

 which M. D'Arcet gives in case fire occurs in such a theatre, where 

 the stage opening can be shut at pleasure, by a metallic screen, 

 constructed of wire sixteen hundredths of an inch in thickness, and 

 with square intervals about two inches in width. Suppose the fire 

 to commence with the decorations upon the stage, the immediate 

 help which should always be at hand should be applied, and the 

 firemen sent for; all means should be taken to quell the flames, 

 until the hope of extinguishing the fire is gone : the system should 

 then be changed; the ventilations over the body of the theatre are 

 to be closed, the screen lowered, all the doors into the lower part of 

 the body of the theatre oj)ened to admit air ; the ventilating flue 

 over the stage must be opened, and the glass of the sky-lights and 

 upper windows of that part broken by stones, or otherwise : a 



