Abel Foullon

Abel Foullon was a writer, director of the Mint for Henry II of France and also an engineer to the king of France after Leonardo da Vinci. In 1545 he married Catherine Clouet, the daughter of the portrait painter Jean Clouet and sister of the portrait painter François Clouet. Their son Benjamin Foullon or Foulon also became a portrait painter and miniaturist.

Invention and patenting of the holometer

Foullon invented a holometre, an instrument for making of angular measurements for surveying. In 1551, Henry II granted Foullon a 10-year exclusive patent monopoly on the holometer in exchange for publishing a description of it. A description of an invention in a patent is called a patent “specification”. This first patent specification was entitled "Usage & Description de l'holomètre". Publication was delayed until after the patent expired in 1561.