class Length YARD = { :barleycorn => ((1.0 / 3) / 12) / 3, :in => (1.0 / 3) / 12, :ft => 1.0 / 3, :yard => 1.0, :pole => 5.5, :chain => 5.5 * 4, :furlong => 5.5 * 4 * 10, :ml => 5.5 * 4 * 10 * 8, :league => 5.5 * 4 * 10 * 8 * 3, } METRIC =…