The Technical term for the Swamp Cooler is the Evaporative Cooler. Its cooling effect is accomplished by forcing the evaporation of water from a wetted pad with a stream of dry air. As the water evaporates the air temperature is dropped, creating an efficient cooling source.
Evaporative cooling utilizes much less electricity than conventional air conditioning systems and is frequently preferred to refrigerated air conditioning due to the elevated presence of moisture.
In areas where relative humidity is high these systems exhibit some limitations when indoor humidity is driven to uncomfortable levels.
Many variations of this principle are in use today.
These are products commonly recommended by Lincoln Heating and Air Conditioning.
Champion Evaporative Cooler
Commercial Evaporative Cooler