 Tables of logarithms prepared by John Napier in 1614 and 1619 used the period (full stop) as the decimal separator, which was then adopted by Henry Briggs in his influential 17th century work.In France, the full stop was already in use in printing to make Roman numerals more readable, so the comma was chosen.Many other countries, such as Italy, also chose to use the comma to mark the decimal units position.