Friday, January 19, 2007

Nature Carried Away The Bell - I

Man invented the wheel some 5000 years ago - but it is not true that, as popularly believed, Nature never got round to it, Some minute bacteria swim with the aid of their flagella - hairlike structures that thrash behind their bodies, driving them along, Each flagellum is attached at its base to a body within the cell wall that acts like a rotary motor. These motors drive the bacterium, enabling it to swim through liquids or skim across solid surfaces.

Although Nature solved the engineering problems of a rotating axle on a microscopic level, she has never got around to producing a large wheel for her creatures. This may be because the wheel is, in the last analysis, a poor means of locomotion - it is efficient on smooth, tarmac roads but next to useless where there are boulders, tree stumps or boggy ground. As most animals have to contend with uneven terrain daily, it may well be that walking on legs is universally the most efficient means of locomotion. Engineers designing robots that have to move over uneven ground are now abandoning the wheel and looking instead at six-legged, insect-like structures.

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