WARMING AND VENTILATING OCCUPIED BUILDINGS. 



303 



Fiof. 15 . 



wliicli is enough for draught, but does not secure a sufficiently rapid 

 removal of foul air. 



21. Improveme^its to he made in tJie construction of stoves. — The princi- 

 pal defects of all stoves, without exception, are — 



1. Not carrying off foul air as quickly as necessary for health. 



2. Giving too high a temperature to the air which passes through 

 them. 



The means of lessening these faults 

 are — 



1. Making separate ventilatin g sh afts, 

 .heated directly by the stove and the 

 chimney. 



2. Enlarging also the size of the hot- . 

 air passages, and always, when not 

 mpossible, taking the air from the 

 outside of the building in order to pre- 

 vent it from entering through the doors 

 and windows. 



3. Furnishing the stoves with doors, 

 which, being opened after the fire is 

 kindled, change them almost into open 

 fire-j^laces, and cause a strong draught 

 in the chimney, the size of which should 

 be enlarged, without fear of increasing 

 too much the expense for fuel. 



German stoves and those of some 

 French makers have an arrangement 

 of this kind, though still imperfect. 



22. Fire-places and stoves with reversed 

 draught. — In some cases the want of 

 a flue above the fire-place renders it necessary to carry the smoke 

 to a horizontal passage below, which conveys it to the bottom of a 

 vertical flue, placed some distance off. To obtain in such a case a 

 draught at the instant of lighting the fire, it is generally necessary to start 

 a small fire in an opening in the horizontal passage at the foot of the 

 vertical flue, which causes a momentary draught ; the external supply 

 of air to this fire being stopped as soon as it is kindled, in order that, 

 taking air from the horizontal passage alone, it may produce a current 

 which will extend to the chimney or to the stove. But this arrange- 

 ment is often insufiicient, at least unless the extra fire be kept up, which 

 would be very troublesome. 



In houses lighted by gas it is preferable to introduce into the chimney 

 at the occupied story, and not at the level of the lower horizontal pas- 

 sage, gas-jets inclosed in a little metallic chimney 9i| inches to llif 

 inches high, with a separate air-supply, in order to prevent it from 

 being extinguished -by the smoke. Three or four jets, each consuming 



