THE ROYAL DUBLIN SOCIETY 327 



per second, at a distance of 6 feet from any person, or 

 5 feet per second at any other place. A temperature 

 of 6o° F. should be guaranteed, the outer air being at 

 3 2° F., and provision should be made for moistening 

 the air when necessary. These requirements necessi- 

 tated the construction of a number of air shafts in the 

 walls of the building, and proper openings for the fans 

 to be used for propelling the air. 



The new theatre was opened by a conversazione on 

 March the 10th, 1897. In addition to the sum of 

 £5000 paid to the Board of Works towards the cost 

 of the building, the Society spent £2430, mainly on 

 the equipment for heating, lighting and ventilation. 

 The theatre seats 700 persons, but on several 

 occasions room has been found for an audience of 

 1000. Fresh air is taken in at an opening 35 feet 

 above the ground, and forced into the building by an 

 electrically driven fan 5 feet in diameter. The air 

 enters the theatre at twenty-seven openings in the ceil- 

 ing and walls ; these openings have an effective area of 

 92 square feet. The air is removed through openings 

 of about the same area, chiefly under the seats, and is 

 expelled from the building by another electrically driven 

 fan. It has been found by actual measurement that 

 the fans are capable of sending 800,000 cubic feet of 

 air, about 27 tons weight, through the theatre in one 

 hour. It is rarely necessary to use more than half 

 this quantity of air. By means of steam-heated pipes, 

 the air, before it enters the theatre, can be warmed 

 when necessary. Daylight can be excluded by means 

 of a false ceiling which descends below the level of the 

 windows of the lantern in the roof. The Society is 

 indebted to Sir Howard Grubb, f.r.s., for the design 

 for this device. The screen for lantern projections, 

 which has an area of 340 square feet, is capable of 



