▁of ▁measurements , ▁the ▁most ▁frequently ▁referenced ▁of ▁which ▁was ▁the ▁blo it . ▁Def ined ▁as ▁the ▁distance ▁the ▁king ' s ▁favorite ▁pet ▁could ▁run ▁in ▁one ▁hour ▁( sp o of ing ▁a ▁popular ▁legend ▁about ▁the ▁history ▁of ▁the ▁foot ), ▁the ▁length ▁of ▁the ▁blo it ▁varied ▁dram atically , ▁but ▁the ▁one ▁canonical ▁conversion ▁to ▁real - world ▁units ▁puts ▁it ▁at ▁approximately ▁two - third s ▁of ▁a ▁mile ▁( 1 ▁km ). ▁Li qu id ▁volume ▁was ▁measured ▁in ▁glo ops , ▁and ▁temperature ▁in ▁degrees ▁Q ▁( 5 7 ▁° Q ▁is ▁said ▁to ▁be ▁the ▁free zing ▁point ▁of ▁water ). ▁ ▁Pot rz eb ie ▁In ▁issue ▁ 3 3 , ▁Mad ▁published ▁a ▁partial ▁table ▁of ▁the ▁" P ot rz eb ie ▁System ▁of ▁We ights ▁and ▁Me asures " ▁developed ▁by ▁ 1 9 - year - old ▁Donald ▁E . ▁Kn uth , ▁later ▁a ▁f amed ▁computer ▁scient ist . ▁According ▁to ▁Kn uth , ▁the ▁basis ▁of ▁this ▁new ▁revolution ary ▁system ▁is ▁the ▁pot rz eb ie , ▁which ▁equals ▁the ▁thick ness ▁of ▁Mad ▁issue ▁ 2 6 , ▁or ▁ 2 . 2 6 3 3 4 8 5 1 7 4 3 8 1 7 3 2 1 6 4 7 3   mm . ▁ ▁Volume ▁was ▁measured ▁in ▁ng ogn ▁( equal ▁to ▁ 1 0 0 0 ▁cub ic ▁pot rz eb ies ), ▁mass ▁in ▁bl int z