PAPERS ON PHYSICS 299 
CONCLUSIONS 
1. ‘This device is nearly automatic in its operation and does 
control the humidity of indoor air, maintaining a fairly con- 
stant relative humidity of about 35 per cent. during both mod- 
erate and extreme outdoor temperatures. 
2. It is folly to talk of materially increasing the indoor 
humidity of a well-ventilated residence by using the common 
furnace water pan or even by suspending vessels of water 
within registers. Any device which does not evaporate several 
gallons of water daily in a well-ventilated residence is nearly 
useless. 
3. It is not practical to attempt to maintain a relative hu- 
midity of more than about 35 or 40 per cent. during cold 
weather. A higher humidity, if obtainable, results in exces- 
sive frosting of windows and the “‘sweating”’ of walls during 
zero weather. 
4. While granting that the calculated relative humidity 
given above is considerably lower than actually would have 
prevailed but for the humidifier, it still is true that the thirsty 
air would have stolen the additional moisture from every 
available source such as the building itself, the furniture and 
the skin and mucous membrane of the residents. 
5. A temperature of 65° to 68° in the living room or li- 
brary is entirely adequate for most people if the relative hu- 
midity is maintained at 35 per cent or more. 
Yiy 2 
KEEKWY \s 
Sate 
+ Min., for January for 
25 years. 2 
s 
Fig. 3. Average Temperature, Max. 
