482 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Investigations on Light and Heat, made and published wholly or in part witb 

 Appropriation from the Rumford Fund 



XXI. 



EXPERIMENTS AND OBSERVATIONS ON THE SUMMER 

 VENTILATION AND COOLING OF HOSPITALS. 



By ISIoRRiix Wyman. 



Presented November 23, 1894. 



In this climate, the sick in our hospitals often suffer much distress 

 from the excessive heats of summer. Their relief demands more 

 serious attention than it has generally received. 



At first sight it would seem a simple matter by means of the cooling 

 processes known to the arts to surround a sick bed with a cool atmos- 

 phere ; but this atmosphere must be constantly renewed and the incom- 

 ing air as constantly cooled ; this cooling is a difficult problem, and has 

 not been satisfactorily solved by any of these processes. It is much 

 easier to warm our patients in winter than to cool them in summer. 



The three principal ways in which our bodies lose heat are by con- 

 vection, radiation, and evaporation ; but they are efficient in very 

 different degrees. 



Radiation, although effective in the open air with a clear sky, does 

 us but little good as a cooling agent on a warm and muggy day. In 

 our wards, when their walls are near the temperature of our patients, 

 or rather of their clothing, which is really the radiating surface, radia- 

 tion benefits them but little, for these walls of necessity return nearly 

 as much heat as is radiated to them. Neither is radiation sensibly 

 modified by any movement of the surrounding air. 



Convection, as the name implies, is the carrying away of heat; it 

 increases inversely as the temperature of the surrounding air, and 

 directly v^'ith its moisture and velocity. We know well the agreeable 

 sensations on a hot summer's day of the sea breeze, which in a greater 

 or less degree combines these qualities. "We know too how much, 

 on a still, hot day, fanning, which changes neither the moisture nor the 

 temperature of the air, but simply causes more air to move over and 

 come in contact with us, adds to our comfort by displacing the hot and 

 moist air immediately around us. 



