From Febvre and Martin’s The Coming of the Book:
“It was not until the 18th century that the efforts of Fournier and Didot forced the adoption of a definite standard of measurement, the points system, the ‘point’ being 144th the size of the king’s foot. This is the unit of measurement used in typography to this day.” (60)
Febvre, Lucien and Henri-Jean Martin. The Coming of the Book: The Impact of Printing, 1450-1800. Trans. David Gerard. Eds Geoffrey Nowell-Smith and David Wootton. London and Brooklyn: Verso, 2010.