Jean Maritz (1680–1743), also Johan Maritz, was a Swiss inventor, born in Burgdorf, Canton of Bern, who moved to France, becoming "Commissaire des Fontes" at Strasbourg (Commissioner of the King's Foundry),A Dictionary of Military History and the Art of War by André Corvisier p.331 and invented the vertical drilling machine, as well as the horizontal drilling machine for cannons in the 18th century. His inventions revolutionized cannon-making and became a key component of the de Vallière system and contributed to the development of the later Gribeauval system.
Jean Maritz first invented a vertical drilling machine for cannons while in France in 1713.The Pirotechnia of Vannoccio Biringuccio by Vannoccio Biringuccio p.223 An Encyclopaedia of the History of Technology by Ian McNeil, p.396 The vertical drilling method however, in which a cannon was slowly lowered over a turning drill, was very delicate, very time consuming and rather imprecise.Louis Xv's Navy, 1748-1762 by James S. Pritchard p.151-152
He further developed a method for the horizontal drilling of cannons around 1734.50 Military Leaders Who Changed the World by William Weir p.132The gun-founders of England by Charles Foulkes p.17 These methods involved the drilling of a bore from a solid casting.
These inventions were vast improvements over previous methods, which involved founding the cannon around a clay core, which was removed after founding, leading to imprecision and shifting of the core, and therefore poor performance.
The inventions of Jean Maritz gave perfectly straight bores which could perfectly fit the ball diameter, and therefore vastly increase efficiency. In the horizontal method developed by Maritz, the solid-cast cannon itself was revolved horizontally, while the drill remained static, in a method similar to that of a lathe.
The son of Jean Maritz, Jean Maritz II (1712-1790), who had worked with his father on the development of boring, became Inspector General of Gun Foundries in 1755. He is credited with the innovation of the horizontal boring machine which can be seen in these images https://www.photo.rmn.fr/archive/06-526761-2C6NU0PLJPKE.html https://www.photo.rmn.fr/archive/06-526762-2C6NU0PLJZSL.html
The Maritz method would be central in the development of the Gribeauval cannon.Napoleon's Guns, 1792-1815 by René Chartrand, Ray Hutchins p.6
See also John Wilkinson
Notes