494 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



In providing ventilation for the hospital Lariboisiere, in 

 1856, 700 cubic feet of fresh air per hour were considered in- 

 sufficient for one person ; and, at considerable expense, the 

 apparatus was adapted to provide 1400 instead, with entire- 

 ly unsatisfactory results, 2100 cubic feet being necessary for 

 an adult, according to the investigations of the lecturer, and 

 in hospitals much more, even as high as 5250 feet. Such 

 change of air may be effected by difference of temperature or 

 mechanical currents, the extent being dependent upon the 

 size of the openings, crevices of windows, doors, etc. Most 

 exhaustive investigations made by Pettenkofer showed that 

 with a difference of 34 between the external and internal 

 air of a room of 1895 cubic feet capacity, the air was entirely 

 renewed in one hour, and more rapidly with increased differ- 

 ence of temperature ; but by carefully jDasting up the crev- 

 ices it can be reduced to one third the amount. It is espe- 

 cially fortunate, therefore, for the poorer classes, that rooms 

 can not be made air-tight, since want of warmth is less in- 

 jurious than continued breathing of vitiated air. A stove, 

 under favorable circumstances, will introduce 3150 cubic feet 

 of fresh air per hour. Furnishing fuel to the poor in winter 

 is equivalent to furnishing fresh air as well. The results of 

 investigations, by Merker and Schultze, of the air of stables 

 were precisely similar to the preceding. The nature, esjDe- 

 cially the thickness, of the wall in all cases causes variation 

 in the amount of fresh air ; and it also appears that the air 

 of small rooms with few inmates is purer than that of large 

 rooms with many. Ventilation is often neglected because 

 of its inseparable association in the minds of many with 

 draught, while in reality it need only be the proper renewal 

 of the air of closed rooms by currents of insensible velocity. 

 A draught, on the other hand, is the cooling of a limited por- 

 tion of the body, either by stronger currents of air or by ra- 

 diation, as to a cold wall, for example, from which a cold cur- 

 rent of air then seems to reach the body. In the open air 

 much strons:er currents do not suo-o-est a drauQ-ht. Coolinsr 

 but one side of the body disturbs the functions of the vaso- 

 motor nerves, not subject to our control, and they at once be- 

 gin to act as if the whole body were cooled instead of but a 

 part, and the decided change in the circulation of the blood 

 becomes dangerous by its suddenness, just as when a cold 



