17 APRIL 1976, Page 17

Good measure Sir: To relieve A. Waugh's puzzlement ( 3 April),

the metre is not based on the stride either of Latins with duck's disease or Of anybody else. With devilish scientific Conning, it was originally intended to be one ten-millionth of the distance from the equator to the pole, or vice versa. Presumably because nobody attempted either journey (somebody would, now), it was later defined as something to do with the wavelength, in vacuo of course, of the orange radiation of the krypton-86 atom. I fear that A. Waugh will nevereven have seen a krypton-86 atom, but he certainly ought to know about the platinum-iridium bar in Paris, where short measure is unknown. W. S. Brownlie

19 Hunterhill Road, Paisley