where did the saying rule of thumb come from
Rule of thumb A modern folk etymology holds that the phrase derives from the maximum width of a stick allowed for wife-beating under English law; this belief may have originated in a rumored statement by the eighteenth-century judge Sir Francis Buller that a man may beat his wife with a stick no wider than his thumb. The rumor produced numerous jokes and satirical cartoons at Buller's expense; however, there is no record that he made such a statement.
To the nines The phrase is said to be Scots in origin.[2] The earliest written example of the phrase is from the 1719 Epistle to Ramsay by the Scottish poet William Hamilton: