[sHAw] RELATIVE HUMIDITY 125 



Que., and some of the results are indicated in the tables given at the end 

 of these notes. It was found that Hill's "comfort factor" was a very- 

 suitable quantity for gauging comfort, while consultations of tempera- 

 ture and humidity only, were very misleading in all cases where the air 

 circulation was either very slow or exceptionally brisk. In con- 

 sidering the humidity alone, it was found most satisfactory t use 

 "vapour pressure" rather than the "absolute humidity" or the "rela- 

 tive humidity." 



3. Recommendations Concerning the Recording of Hu- 

 midity. It has been concluded from these considerations and from the 

 experiments to which reference has been made, that strong recom- 

 mendations for improvement should be made. 



In all ordinary chemical and physical problems involving ques- 

 tions of humidity, it is recommended that the aqueous vapour pressure 

 be considered and recorded as the fundamental quantity for con- 

 sideration in conjunction with the temperature, the absolute and the 

 relative humidity being taken as secondary quantities which can be 

 determined from the usual tables when actually required. 



With reference to meteorological reports and the data needed by 

 physiologists for determining the best conditions for health, it is 

 strongly recommended that the rate of heat loss from a standard type of 

 wet bulb, at body temperature, expressed in millicalories per sq. cm. per 

 sec, as suggested by Hill,^ be adopted universally as a standard quan- 

 tity for determining the comfort of the atmosphere. Subsidiary 

 figures should be recorded showing — along with the temperature and 

 the barometric pressure — the vapour pressure and the velocity of air 

 circulation at the time and place of observation. This "comfort 

 factor" if systematically employed, could replace in popular use the 

 present unsatisfactory "temperature" and "humidity." Kata- 

 thermometers, or other instruments capable of giving this quantity, 

 could in time be manufactured, operated and understood in general, 

 as readily as the ordinary thermometers and hygrometers. 



At regular observing stations, the various subsidiary records 

 mentioned could be determined accurately by the usual meteoro- 

 logical instruments, but for the casual observer it is important to note 

 that the vapour pressure, and the velocity of air circulation (includ- 

 ing, if desired, the relative humidity), may be obtained from this 

 "comfort factor" by empirical formulae which are as reliable as those 

 at present used for the customary determinations of humidity. 



4. Observations with Improved Hygrometric Methods. 

 A comprehensive set of experiments is being carried out with the object 



'Hill, Griffith and Flack, loc. cit. 



