WYMAN. — COOLING OP HOSPITALS. 483 



The Cambridge Hospital is warmed by air heated in passing over 

 pipes in which hot water circulates, enclosed in heating boxes ; it is 

 obvious that the substitution of cold water for hot water in these pipes 

 would cool, more or less, the air on its way to the wards. 



It was thought worth while to determine by experiment what influ- 

 ence this previous cooling might have on the comfort of our patients 

 as compared with air of the same velocity from the open, unchanged 

 in temperature or moisture. 



An air-chamber extends under the whole ward ; it is devoted 

 exclusively to the purpose of receiving the air for ventilation and 

 distributing it equally through the heating boxes and ten registers to 

 the ward above. This air-chamber is well lighted, and is kept scrupu- 

 lously clean ; nothing is allowed to be placed in it under any pretence 

 whatever. It is generally cooler in the summer than the atmosphere ; 

 water from the city water service is also cooler by several degrees, in 

 the early summer, than the air. By connecting the city main with 

 the pipes in the heating boxes, and allowing the water flowing through 

 them to run to waste, they become in some degree air-coolers. 



On the 21st of May, 1893, all windows and openings in the air- 

 chamber were carefully closed, and the water from the main let on. 

 At 3 p. M. the external thermometer was at 84° F. ; there was na 

 wind, and the patients were sufi^ering from the heat. The tempera- 

 ture of the air-chamber was 67" F. ; the water as it entered the cool- 

 ing boxes, 57-58°. The electric fan, 36 inches in diameter, driving 

 the air into the air-chamber, was put in motion, making 500 revolu- 

 tions with an air-moving power of 10,200 cubic feet a minute. At 

 4 p. M. the air entering the ward at the registers was at 71° F. 



During this hour 400,000 cubic feet of air, as measured by a 

 Casella's air-meter, was thrown into the ward through the ten regis- 

 ters ; a quantity sufficient to fill the ward of 21,000 cubic feet twenty 

 times an hour, — once in three minutes. 



The result was satisfactory ; the comfort of the patients was mani- 

 festly improved. 



But it must be observed that the cooling surfaces were, first, the ten 

 cooling boxes of 30 square feet each at 57-58° F., and, secondly, the 

 floor and walls of the air-chamber, the two together amounting to about 

 3,300 square feet. The temperature of these walls could not well be 

 determined ; but as they had not been exposed to much increase of 

 heat since the winter, they may be assumed to have been about that 

 of the water supply, then 58° (in winter it is about 50°). At the out- 

 set then we had the air-chamber full of cool air and a cooling surface 



