WAKMING AND VENTILATION. 281 



Note. — The builder actually gave smaller sectional areas to the flues ; 

 still the intended results have been secured. 



In the first series of collecting-flues iu each story, where the velocity 

 is to be 39 inches a second, the sectional area should be — 



Square feet. 

 For the second story, amount to be renewed in 1 second 



= 39 cubic feet, sectional area 12 



For the third story, amount to be renewed in 1 second 



= 20 cubic feet, sectional area 6 



In the two collecting-flues terminating at the bottom of the general 

 veutilating-chimney, the required velocity being 4 feet a second, their 

 total sectional area was fixed at — 



Square feet. 



For the second story 10 



For the third story 5 



15 



The latter flues carry the foul air to the bottom of the chimney, which 

 is 56 feet high, and has a sectional area of 11 square feet. The two 

 smoke pipes being each 8 inches in diameter, or 2 feet in circumference, 

 and having consequently 50x2=112 square feet of surface exposed to 

 cooling, were not able, even in ordinary weather, to sustain the draught 

 of the chimney, and a small auxiliary fire was deemed necessary. To this 

 was given a surface of about 100 square inches, which, when burning 3.J 

 pounds of coal an hour, carried oft", on an average, 140,000 cubic feet of 

 air an hour in the second story, and 70,000 in the third story. If the 

 dimensions of the ventilating-flues given to the builder had been followed 

 instead of being reduced to 16 square feet in the second story and 8 in 

 the third, it is evident that the amount of air carried off would greatly 

 exceed the prescribed amount, which shows that the rules which have 

 been given allow for even serious defects in construction. 



The observations made in this building in regard to the results of 

 warming and ventilation lead to this important conclusion, that with, 

 well-made heaters and a i^roperly- arranged system of ventilatiou, school- 

 rooms with 350 cubic feet of air to each pupil may be comfortably 

 warmed and ventilated by the use of no more fuel than is required for 

 the injurious heat obtained from the cast-iron stoves used in most schools. 



ADULT-SCnOOLS. 



G3. Similar plans should be adopted for adult-schools ; the only change 

 to be made consists in increasing to 500 or 700 cubic feet the amount of 

 air to be carried off every hour for each person 5 or, in other words, to 

 increase the size of the foul and fresh air flues. 



NIGHT-SCHOOLS OF DESIGN. 



04. These present a peculiar difficulty in changing the air and mod- 

 erating the temperature, in consequence of the large number of lights 



