Multitasking: "Dude, You're A Manhole Cover!"

Manhole covers (personhole covers, I guess, to us pc types) are an original example of multitasking. And they lay right at our feet. They allow access to workers for maintenance, rainwater to run off (and theoreticaly not into one's basement), sewers to ventilate gases and stop hapless people from falling in.

Ancient Romans began the practice of stopping its citizens from falling into sewage. And it caught on. The square knobs are said to have been popular since the days of horse and buggies, the knobs being footholds for horse's hooves. Weighing over 50 kg, these artifacts have captured the imagination of people the world over, who collect photos of various designs. Modern race cars are so aerodynamically designed that manhole covers have to be welded down to avoid being lifted by the suction caused when the cars pass over them. And the same when the Queen visits, as part of security precautions (not suction-related).

Microsoft incorporated the question: "Why are manhole covers round?" into interview questions, to gauge how people tackle a question with many right answers. (Cannot fall into it's opening, strong, material efficient and cheap to manufacture, don't need to be rotated to fit, can be rolled when moved, etc.)

Note: in recent years, as metal shortages mounted, manhole cover theft has become a worldwide phenomena. In China Shakes the World, James Kynge describes the phenomenon:

"...in the several weeks beginning in mid-February 2004, when, slowly at first but with mounting velocity, manhole covers started to disappear from roads and pavements around the world. As Chinese demand drove up the price of scrap metal to record levels, thieves almost everywhere had the same idea. As darkness fell, they levered up the iron covers and sold them to local merchants, who cut them up and loaded them onto ships to China. The first displacements were felt in Taiwan, the island just off China's southeast coast. The next were in other neighbors such as Mongolia and Kyrgyzstan... Wherever the sun set, pilferers worked to satisfy China's hunger. More than 150 covers disappeared during one month in Chicago. Scotland's "great drain robbery" saw more than a hundred vanish in a few days. From Montreal to Gloucester to Kuala Lumpur, unsuspecting pedestrians stumbled into holes."

Because of this demand, it is said that 8 people in China were killed by falling into open manholes in 1994.

An interesting footnote, for those of you still reading. The word manhole was first used for access holes between the decks of the old, all-male sailing ships and had nothing to do with sewers.

So today, as you juggle many tasks at once, remember the humble manhole cover. We, like them, serve many purposes. And on our best day, we may even prevent someone else from falling down a hole.

 (A contribution from my bro Rick. Evidently a fish lover!)