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Show When Is Draft Not a Draft? Dr.HiUleUs ' "When Is a. draft not a draft? that Is, when are cooliiig breezes beneficial to the body, and when will they cause colds?" This la a question ques-tion every house-wife house-wife ponders whenever she exposes ex-poses her children chil-dren to air currents cur-rents during linl weather. The an. swer, according to ' the Holland Institute of Ther-mology Ther-mology of Holland, Hol-land, -, M 1 c li., opens up one of Dr. E. Vernen Hill. . the most fascinating phases of mod-ern mod-ern air conditionals' science. ' "A draft la a' current of ntr which, by reason of Its low temperature, low humidity, or high velocity, or any velocity, or any comblnntion of these three, removes a greater amomit of heat from the part of the body It comes In contact with than the sur face of that pnrt normally give oft." This definition was formulated by J)r. E. Vernon Hill, of Chlengo, who Is both a physician and one of tho fore-moha fore-moha nlr-condltlonlug engineers In the country. It : means, among other things, that If air motion Is to be used as a method of cooling a home or other oth-er building, the air which is kept moving mov-ing must not be too low in temper, oture. . y ,( . This principle' is followed in the so- i lutlon of many Judcstriul, problems where, without any reduction of the actual temperature of the air, U Is kept moving nt such a velocity that It producer a cooling effect upon the ! workers. The same principle, accord-1 Ing to the Holland Institute of Tlier- j mology, can bo applied, without complicated com-plicated and expensive nmehtnery, to.' the cooling of the home during hot 1 weather.. In fact, this Is just what Is done in j the modern "vaporalre" heating sys-tern.' sys-tern.' A small electrified propeller unit j Is Installed In the, central lieatlu;- plnnt and. is run on hot days tr fcccy tip lively circulation of the air through j nil tlie rooms of tlio home. Engineer- j Ing'tests have shown that even though i the temperature of the air Is not actually ac-tually reduced by elaborate refrigerating refriger-ating or dehumldifylng machinery, this air motion produces a comfort effect ef-fect 14 per cent better llinn that of the same air If It Is stagnant. tty this means, the engineers of the Holland Institute point out, the warm nir. circulating heating plant Is replaced re-placed by an all-year-round air con-! dlllonlng system. For during the winter the rapid motion of the air ( passing through the heat generator 1 tip to the rooms Increases the rapidity rapid-ity with which the home can he ! warmed and markedly reduces fuel j costs by eliminating the need for fore- j Ing the heater and by operating with ; a large volume of moderately warmed : ; nlr Instead of a simill volume of super- 1 heated air. j |