How Man Defeated the Heat

Humans evolved in hot, humid tropical regions. The body of most animals are able to produce heat naturally which is insulated by fur. When an animal begins to overheat it usually begins panting. The process rags air across their moist tongues which in turn causes the moisture on their tongues to evaporate cooling the tongue off. Blood pumped through the tongue is then cooled and in turn cycles through the body where the rest is cooled off. Since humans evolved in areas where it was never cold there was no need for fur. Exposed naked skin allowed heat to be given off. More effective was perspiration which caused the skin to become moist, the evaporation of that moisture cooling the body off.

Aside from sweating humans had very few options to keep themselves cool on hot days. Standing in the shade was one, which kept direct sunlight off of the body. Water was another. Taking a dunk in water put far more moisture onto the skin than sweat did, and in the case of rivers which originated from the melting snow on top of mountains the water itself could be cold. The ocean itself could be 20° cooler than the air. Ancient civilizations discovered that water fountains produced cool air. This is caused by the water itself cooling off the nearby air, the spray from the fountains causing the skin to become moist and vortexes forming around the moving sprays of water causing a slight breeze near the fountain. Fanning was yet another early way for man to cool himself off. Humans knew that a breeze was effective in cooling off the body, specifically by causing moisture on the skin to evaporate faster. It was eventually discovered that by waving ones hands one caused a small bit of wind. And by holding a large stuff leaf one caused even more wind. One of the earliest uses of paper was to create hand held fans.

Keeping the homes cool during the summer could be a problem. Houses were designed to keep the insides warm during cold weather, but this technology could make them act more like an oven in hot weather. About the only thing that cold be done was to keep doors and windows open. Window shades were effective in bouncing the suns light away when the sun was directly facing the window. Leaving windows and doors open allowed unwanted insects to enter houses. In 1861 a wire mesh was invented for the purpose of sifting flour. The company that manufactured the mesh soon realized it could be sold in window sized sheets that allowed air into the homes but had holes too small for insects to enter.

Around the same time as the invention of window screens a combination of advances in transportation and insulation enabled companies to cut large blocks of ice from frozen winter lakes, transport them in insulated box cars to warehouses across the country, and store them there throughout the summer. Insulated by sawdust the ice was kept from melting. It would then be sold in chunks to restaurants and homes who would place them inside of ice boxes. Ice boxes were the earliest form of refrigerator that kept food cool with insulation and the large block of ice stored on the top. Ice boxes remained in homes long after air conditioning was discovered. The original air conditioners compressed gas into tubes with pumps which in turn caused the gas to grow cold. Air was then pumped past the tubes which in turn cooled the room off. Since the machinery in this process was large and bulky it was only used by companies, usually to store large quantities of food in freezers, and only occasionally to cool rooms with people. Even as technology allowed more practical air conditioning homes did not use it. Now instead of transporting ice from frozen lakes companies could use air conditioning to freeze their own ice, which was then sold to ice boxes. The invention of Freon gas allowed for small safe refrigeration units and air conditioners, but these would not be affordable for home use until the 1950's.

What was used to cool off in homes was the electric fan. Electric fans had curved blades that when rotated acted like a screw and drew air past them an in turn causing a breeze. It is a myth that fans could cool off a room, other than window fans which drew hot air out of rooms. Window fans were only effective if the air outside was cooler than inside. The only reason fans work is that they cause a breeze which evaporates moisture on the skin. While having a fan blowing directly on you make make it seem like it is cooling off the room, it does not actually do anything to the air temperature but make it slightly rise. Newer cooling systems combine fans with air conditioners to circulate cool air throughout a room.