7:26 Transactions of tee American Institute. 



Cubic feet. 



Schook, for each cliikl, per liour 400 to 500 



Schools, for each adult, per hour 800 to 1,000 



Meeting halls, for each person, per hour 1,000 to 2,000 



Theatres, for each person, per hour 1,400 to 1,700 



Prisons, for each person, per hour 1,700 



Worksho})s, ordinary trades, per hour 2,000 



"Workshops, unhealthy trades, per hour 3,500 



Ordinary hospitals, per hour 2,000 to 2,400 



Hospitals for epidemic cases 5,000 



The temperature of the air in places abundantly ventilated, and 

 having a continual renewal of air, can be maintained at a higher 

 point than in rooms not well ventilated ; but, as a general rule, the 

 temperature should not exceed the degrees here given (without frac- 

 tions, on both the Fahrenheit and Centigrade thermometer). 



Fahrenheit. Centigrade. 



Workshops 59, or 15 



Hospitals 61 to 64, or 16 to 18 



Schools 06 to 68, or 19 to 20 



Meeting rooms 66 to 72, or 19 to 22 



Theatres 68 to 72, or 20 to 22 



The fresh air supplied should be at nearly the same temperature as 

 the one to be maintained in the room ; but if there is a large cooling 

 surface of glass in windows, it has to be increased to as high as 

 eighty-tive degrees to ninety-five degrees Fahrenheit (thirty-six degrees 

 to thirty -five degrees Centigrade), oi- diminished where the room is 

 partially heated by a large number of artificial lights, or by presence 

 of a large concourse of persons. For the purpose of regulating the 

 temperature, the supplied air, warmed by some heating apparatus, 

 has to be received first into a chamber into which cold air can be 

 introduced for mixing with it. It has been found, by practice as 

 well as by theory, that the average velocity of air in the flue is pro- 

 portional to the square root of the height of the chimney, and the 

 square root of the excess of the temperature of the air in the flue 

 over that of the external air ; having the area of the chimney, it is 

 easy to estimate the volume of air extracted. 



The position of the openingo for the admission and removal of the 

 air is a point of great importance. None of these should be on a 

 level with the floor where they would be obstructed by sweepings 

 and rubbish. All the openings for the admission of air, whether 

 warm or cold, should be placed near the ceiling, or at such height 

 that no person may receive the impression of a draft. Openings for 



