Friday, December 5, 2008

Quote of the Week: Man and Fly Walk at the Same Speed (Kind Of)

From On Growth and Form (Sir D'Arcy Thompson):
An apparently simple problem, much less simple than it looks, lies in the act of walking ... The smaller man, or smaller animal, goes slower than the larger, but only in the ratio of the square roots of their linear dimensions ... M. Delisle saw a fly walk 3 in. in half-a-second; this was good steady walking. When we walk 5 miles an hour we go about 99 in. in a second, or 88/6 = 14*7 times the pace of M. Delisle's fly. We should walk at just about the fly's pace if our stature were 1/(14*7) squared, or 1/216 of our present height ... say 76/216 in., or one-third of an inch high. Let us note in passing that the number of legs does not matter, any more than the number of wheels to a coach; the centipede runs none the faster for all his hundred legs.
From an Abridged Edition, J.T. Bonner, editor, Cambridge University Press, 1961, pg. 28-9. On Growth and Form was originally published in 1917.

No comments: