54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 60 



ture and moisture. Thus those suffering from heart disease and 

 bronchitis — when shut in the cabinet- — were comfortable so long as 

 the temperature readings lay between 8° and 20 C, in spite of the 

 C0 2 rising to 1.57 per cent. They were very sensitive to high read- 

 ings, and endured less heat (for example, 20° to 2J C), and for 

 much less time (for example, only 40 to 50 minutes), than healthy 

 men. They complained of dizziness and were generally uneasy. 

 Normal men became uncomfortable when the temperature rose to 

 from 2/° to 31 ° C, with a relative humidity of 51 to 60. The skin 

 temperature of the forehead rose 2° to 3 C, and the relative mois- 

 ture of the air in contact with the skin as taken with a hygrometer 

 under the clothes rose 20 to 30 per cent. 



Benedict ' has shown that a man can live many days in a closed 

 calorimeter chamber in comfort, without damage to his health, and 

 having not the slightest cognizance of any defect in ventilation when 

 this is so reduced that the C0 2 accumulates to from 1 to 2 per cent — 

 that is, so long as the air of the chamber is kept cool and dry. 

 Zuntz ' suggested that this result might be due to the circulation of 

 the air through the H 2 S0 4 driers and the destruction thereby of 

 organic chemical poison, but no H 2 S0 4 driers were used in the ex- 

 periments of Haldane and Lorrain Smith, Paul, Ercklentz and in 

 our own experiments, in which all discomfort was prevented by 

 cooling the air. 



Our experimental chamber was constructed of wood, with large 

 glass observation windows. It was rendered air-tight by filling all 

 cracks with putty and by pasting layers of brown paper over the 

 wood. The chamber was entered through a man-hole which was 

 closed by a shutter. 



On one side of the chamber were fixed two small electric heaters, 

 and a tin containing water was placed on these in order to saturate 

 the air with water vapor. On another side of the chamber was 

 placed a large radiator through which cold water could be circulated 

 when required, so as to cool the chamber. In the roof were fixed 

 three electric fans, one big and two small, by means of which the 

 air of the chamber could be effectually stirred. A wet- and a dry- 

 bulb thermometer were placed within, and readings were taken 

 periodically after whirling these round in the air of the chamber. 



'Bull. 175, U. S. Dept. Agric, p. 235. 



- Report Brit. Asso. Adv. Sci., 191 1, p. 543. 



