488 PROCEEDINGS OF THE AMERICAN ACADEMY. 



the temperature of the body may remain nearly normal in an exces- 

 sively hot atmosphere, — even more than 200° F. 



In the present atmosphere of mixed air and aqueous vapor, with 

 which it is never saturated, evaporation and convection must coexist. 

 So long as the expired air is loaded with moisture, and the skin per- 

 forms its perspiratory function, and the movement of the surrounding 

 air is under our own control, if, so to speak, we own a breeze, we may 

 confidently rely on our ability to dispense its comforting and refreshing 

 influences to the patients in our hospital. 



The following observations with the wet and dry bulb thermometer 

 may serve to illustrate the cooling of a moist surface. June 17, 1894, 

 a thermometer in a still room was at 78° F. ; after covering the bulb 

 with a piece of thin cotton cloth moistened with water, and fanning it 

 for five minutes with a common fan, it fell to 72°, — a difference of 6°. 

 The same thermometer on the same day at 99°, treated in the same 

 way, fell to 77°, — a difference of 12°. A thermometer in the open air 

 in the shade, July 13, 1894, with a gentle breeze, was at 95° ; with a 

 moistened bulb, at 73°, — a difference of 12°. The relative humidity 

 at the same time was 53%. 



But the air must be in motion. A perspiring patient in still air is 

 surrounded by an atmosphere permeated by much aqueous vapor; this 

 must be diffused and carried away from the neighborhood by the 

 continued arrival of fresh drier air, to get the full cooling effect due 

 to evaporation. 



It is in this way that simple agitation of the air in a warm still 

 room brings relief, as with a common fan, or the rotary fan of the 

 shops, or the Indian punkah. So it is with a ride in the open elec- 

 tric car on a hot day ; the relief is immediate. There is no atmos- 

 pheric change either in temperature or in moisture ; it makes no 

 difference whether we move through the air, or the air moves by us, 

 the sense of cooling is the same. In both, we are surrounded by air 

 constantly renewed, bringing with it the pleasurable sensations and 

 invigorating influences belonging to a freely moving atmosphere. 



What these influences are to those in health we know; what they 

 are to those languishing on beds of sickness, those only who have ex- 

 perienced them can fully appreciate. That the patients in our hospi- 

 tal have derived much comfort from them, their repeated declarations 

 fully prove. Besides the physical comfort they give, — like the sug- 

 gestions of flowers and music, with which the sufferings of the sick are 

 now so often soothed, — these large volumes of air fresh from the fields 

 seem to hold up to the mind of the convalescents suggestions of other 



