It started with Latin, of course. Everything starts with Latin despite what the Greeks want to believe. *wink* It is often claimed that the symbol traces its origins to the symbol ℔, an abbreviation of the Roman term libra pondo , which translates as "pound weight". This abbreviation was printed with a dedicated ligature type, with a horizontal line across, so that the lowercase letter "l" would not be mistaken for the numeral "1": ℔. Ultimately, the symbol was reduced for clarity as an overlay of two horizontal strokes "=" across two forward-slash-like strokes "//". Then it started hanging around as the musical note sharp. Composers were the cool kids on the block with their sharps and their genius arrangements including other musical notes. And then in the late 1800's book-keeping manuals and courses differentiated its use between serving as a number symbol and serving as a symbol for weight - pounds. We Americans