Historically, the width of the thumb, or "thumb's breadth", was used as the equivalent of an inch in the cloth trade; similar expressions existed in Latin and French as well. The thumb has also been used in brewing beer, to gauge the heat of the brewing vat. Ebenezer Cobham Brewer writes that "rule of thumb" means a "rough measurement". He says that "Ladies often measure yard lengths by their thumb. Indeed, the expression 'sixteen nails make a yard' seems to point to the thumb-nail as a standard" and that "Countrymen always measure by their thumb". According to "Phrasefinder", "The phrase joins the whole nine yards as one that probably derives from some form of measurement but which is unlikely ever to be definitively pinned down".