Beviek & briatollah, we might have had one of those swamp coolers when I lived in Lawton for 6 months back when I had to be in the Army. I know for sure we had one in El Paso. The ElPaso one had a thing like a furnace filter in shape that was made of straw. Water got dripped on it it as air was pulled through it to be cooled by the evaporation of the water. Got to be good friends with the manager of the apts who was also in the army. We still write eath other.The Wikipedia article on them might help.