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

172 THE HEALTH BULLETIN.former are removed the feet are protectedby dry shoes which are nonconductorsof heat, and therefore protectthe body.Even though the soles of the shoesare not completely wet so as to makethe best conductors of heat, the presenceof a layer of wet leather nextto the ground constitutes a refrigeratingapparatus which rapidly absorbsheat. Salt on the ice in an ice-creamfreezer causes the ice to melt andthereby abstracts the heat from theice-cream holder and causes the icecream in turn to freeze. The armycanteen is a metal holder for watersurrounded by a cotton or woolen cloth.By dipping the whole canteen in waterthis cloth is made wet, and thenwhen hung in the air the water evaporates,and in doing so becomes arefrigerating apparatus causing thewater within the canteen to becomecool and fit to drink. A similararrangement is very common in thewest, and possibly other parts of thecountry, especially among those whouse automobiles. It is a bag abouttwelve by eighteen inches, usuallymade of strong, thick canvas. Thishag is thoroughly soaked in water, andwhen it is filled with about two gallonsof water, sufficient water leaksthrough to evaporate and keep thewater within at a temperature suitablefor drinking purposes. This sameresult is obtained in various partsof the world by the use of a porous,earthenware jar, which will allowsufficient moisture to escape throughthe pores to evaporate and cool thewater within.We are more familiar with thiscooling effect in the case of alcohol,or cologne, which is largely alcohol.We know that if we put cologne onour foreheads when we have a headache,it has the effect of cooling theforehead and giving relief. This isbecause the cologne evaporates morerapidly than water does. Also theprovision of nature by which we perspirein hot weather is for the samepurpose, namely, that the slight moistureon the skin, by continual evaporation,shall cool the skin and therebyreduce the temperature of the body.When even a part of the soles ofour shoes is wet we have a refrigeratingapparatus which rapidly reducesthe temperature of the whole body.is not necessary that the feet or stockingsthemselves be wet, because thesame results to a certain degree willbe accomplished even though thewhole sole of the shoe may not bewet. There is nothing in water thatgives a cold or reduces temperature.If we kept our feet in water that wasof the temperature of the body it wouldnot abstract any cold from us and wewould not suffer thereby. But thetemperature of the damp earth or ofthe rain is lower than that of ourbodies, and, as shown above, the wetshoe by evaporation reduces the temperatureeven lower.Everyone should wear in damp andcold weather sensible shoes with fairlythick soles; the thicker the sole, thethicker the layer of dry, nonconductingleather.ItCare in the protection of ourlower extremities may seem too simplea thing to think much about, but itwill prevent a very large proportionof the ordinary headaches, indigestions,and colds that we have, and willalso make us far less liable to attacksfrom other diseases, including tuberculosis,to which our systems arelikely to succumb.