All electrical engineers know that ``ELI the ICE man'' was the guy who delivered ICE to people's houses before electricity and refrigerators were available. But few people know the rest of the story. *

As people became more greedy for comfort, they wanted more ICE delivered to cool their houses in the summer. So ELI became super busy delivering ICE, as it turned out each house would need 5 tons of ICE per day to keep it comfortably cool. Years later, when electricity and air conditioners became available, the tradition was kept. Nowadays the air conditioners are rated in "tons", where 1 ton=12,000 Btu** per hour is the power needed to milt one ton of ICE per day. So if you run a 5-ton air conditioner continuously, the cooling you get is equivalent to melting 5 tons of ICE delivered to your house every day, by who else but ELI the ICE man.

* Courtesy of Professor Tanenbaum, who kindly provided the latter part of the story.

** Btu (British thermal unit) is the amount of energy needed to heat 1 pound (0.454 kg) of water by 1 degree F (0.556 degree C).