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The Health bulletin [serial] - University of North Carolina at Chapel Hill

The Health bulletin [serial] - University of North Carolina at Chapel Hill

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172 THE HEALTH BULLETIN.former are removed the feet are protectedby dry shoes which are nonconductors<strong>of</strong> he<strong>at</strong>, and therefore protectthe body.Even though the soles <strong>of</strong> the shoesare not completely wet so as to makethe best conductors <strong>of</strong> he<strong>at</strong>, the presence<strong>of</strong> a layer <strong>of</strong> wet le<strong>at</strong>her nextto the ground constitutes a refriger<strong>at</strong>ingappar<strong>at</strong>us which rapidly absorbshe<strong>at</strong>. Salt on the ice in an ice-creamfreezer causes the ice to melt andthereby abstracts the he<strong>at</strong> from theice-cream holder and causes the icecream in turn to freeze. <strong>The</strong> armycanteen is a metal holder for w<strong>at</strong>ersurrounded by a cotton or woolen cloth.By dipping the whole canteen in w<strong>at</strong>erthis cloth is made wet, and thenwhen hung in the air the w<strong>at</strong>er evapor<strong>at</strong>es,and in doing so becomes arefriger<strong>at</strong>ing appar<strong>at</strong>us causing thew<strong>at</strong>er within the canteen to becomecool and fit to drink. A similararrangement is very common in thewest, and possibly other parts <strong>of</strong> thecountry, especially among those whouse automobiles. It is a bag abouttwelve by eighteen inches, usuallymade <strong>of</strong> strong, thick canvas. Thishag is thoroughly soaked in w<strong>at</strong>er, andwhen it is filled with about two gallons<strong>of</strong> w<strong>at</strong>er, sufficient w<strong>at</strong>er leaksthrough to evapor<strong>at</strong>e and keep thew<strong>at</strong>er within <strong>at</strong> a temper<strong>at</strong>ure suitablefor drinking purposes. This sameresult is obtained in various parts<strong>of</strong> the world by the use <strong>of</strong> a porous,earthenware jar, which will allowsufficient moisture to escape throughthe pores to evapor<strong>at</strong>e and cool thew<strong>at</strong>er within.We are more familiar with thiscooling effect in the case <strong>of</strong> alcohol,or cologne, which is largely alcohol.We know th<strong>at</strong> if we put cologne onour foreheads when we have a headache,it has the effect <strong>of</strong> cooling theforehead and giving relief. This isbecause the cologne evapor<strong>at</strong>es morerapidly than w<strong>at</strong>er does. Also theprovision <strong>of</strong> n<strong>at</strong>ure by which we perspirein hot we<strong>at</strong>her is for the samepurpose, namely, th<strong>at</strong> the slight moistureon the skin, by continual evapor<strong>at</strong>ion,shall cool the skin and therebyreduce the temper<strong>at</strong>ure <strong>of</strong> the body.When even a part <strong>of</strong> the soles <strong>of</strong>our shoes is wet we have a refriger<strong>at</strong>ingappar<strong>at</strong>us which rapidly reducesthe temper<strong>at</strong>ure <strong>of</strong> the whole body.is not necessary th<strong>at</strong> the feet or stockingsthemselves be wet, because thesame results to a certain degree willbe accomplished even though thewhole sole <strong>of</strong> the shoe may not bewet. <strong>The</strong>re is nothing in w<strong>at</strong>er th<strong>at</strong>gives a cold or reduces temper<strong>at</strong>ure.If we kept our feet in w<strong>at</strong>er th<strong>at</strong> was<strong>of</strong> the temper<strong>at</strong>ure <strong>of</strong> the body it wouldnot abstract any cold from us and wewould not suffer thereby. But thetemper<strong>at</strong>ure <strong>of</strong> the damp earth or <strong>of</strong>the rain is lower than th<strong>at</strong> <strong>of</strong> ourbodies, and, as shown above, the wetshoe by evapor<strong>at</strong>ion reduces the temper<strong>at</strong>ureeven lower.Everyone should wear in damp andcold we<strong>at</strong>her sensible shoes with fairlythick soles; the thicker the sole, thethicker the layer <strong>of</strong> dry, nonconductingle<strong>at</strong>her.ItCare in the protection <strong>of</strong> ourlower extremities may seem too simplea thing to think much about, but itwill prevent a very large proportion<strong>of</strong> the ordinary headaches, indigestions,and colds th<strong>at</strong> we have, and willalso make us far less liable to <strong>at</strong>tacksfrom other diseases, including tuberculosis,to which our systems arelikely to succumb.

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