360 



HOME HYGIENE. 



shape. The location of the house, the prevail- 

 ing winds, the height of the chimney with re- 

 spect to the surrounding buildings, govern the 

 " draught " in a high degree. The direction of 

 the air-current is quite likely to be downward 

 in an unheated chimney. Some examinations 

 recently made by the writer gave the follow- 

 ing results: In a chimney with one side con- 

 nected with the flue of a furnace, on a still 

 day, there was a slight downward current 

 of thirty-five cubic feet per minute. The cur- 

 rent was not sufficient to turn the fan of the 

 anemometer, when placed a few inches in front 



FIG. 2. FRONT ELEVATION, SHOWING SHOKE AND Ans 

 FLUES. (Galton.) 



of the fireplace. At this time the inward cur- 

 rent from the register alongside the chimney 

 showed a velocity of 130 feet per minute. On 

 a windy day the upward current in the same 

 chimney was 400 cubic feet per minute. In a 

 building in process of construction, examined 

 March 10, 1881, an unheated chimney on the 

 first floor showed a feeble downward current ; 

 the same chimney showed a downward current 

 in the basement of 75 cubic feet per minute. 

 On the first floor of the same house, a chimney 

 which was only slightly heated (the plumber 

 having a fire-pot in the fireplace) showed an 

 upward current of 239 cubic feet per minute. 

 In an adjoining building, an unheated chimney 

 on the first floor showed a downward current 

 of 115 cubic feet per minute, with the doors and 

 windows open. The same chimney, with the 

 doors and windows closed, showed a downward 

 current of 140 cubic feet per minute. These 

 chimneys were to all appearance precisely sim- 

 ilar in construction, and it is evident that the 

 direction of the current in the chimney is largely 

 determined by the amount of heat within, and 

 the prevailing winds without. Various forms of 

 cowls, or hoods, have been devised to protect 

 against downward draughts in chimneys, many 

 of which are excellent, and should by all means 

 be supplied to a chimney which when heated 

 does not show an upward current of at least 



130 to 200 cubic feet per minute. The amount 

 of ventilation in an ordinary house being al- 

 most wholly dependent upon the chimney, it is 

 therefore of the utmost importance that it 

 should be properly constructed and finished. 

 An open grate requires from 500 to 600 cubic 

 feet per minute of fresh air. This is usually 

 supplied through the crevices of the doors and 

 windows. No other form of heating apparatus 

 has as yet been devised which will abstract the 

 same quantity of air from a room ; it is conse- 

 quently the best system of ventilation. The 

 objections urged against it are, in the first place, 

 the dust from the coal and ashes, and, in the 

 second place, its greater expense. As the ad- 

 vantage to be derived from it is so much greater 

 than its attendant evils, the first argument can 

 have but little weight; and, as to its expense, it 

 has been well said that any system of ventila- 

 tion at all worthy of the name costs some- 

 thing, and the expense is therefore a necessary 



FIG. 3. SECTION OF GALTON FIREPLACE AND CHIMNEY. 

 (Lincoln.) 



one. Should the house be provided with double 

 sashes, and the doors be close-fitting, as is the 

 custom in cold climates, it may be advisable to 

 secure the entrance of a sufficient quantity of 



