1734 - Introduction of the Maritz' Machine to bore Naval Guns

Johann Maritz, 54, is a Swiss gun-maker, established as Commissionner of the Royal Foundry at Strasbourg. He first invented a method of vertical drilling twenty-one years ago to replace the old method of casting the gun around a core made of clay. The purpose was to improve bore accuracy but the process was rather slow.

This time, the drilling machine is horizontal. It remains static while the gun revolves around the mandrel. Accuracy is outstanding without impacting foundry productivity.

The navy has immediately been interested in this new sort of gun, precisely bored. There is nothing surprising if one takes into account the huge number of guns used on warships, as well as their pivotal role in naval warfare.

¤ The French navy has likely got around 7,000 guns, the British one around 18,000 or 19,000. As a term of comparison, land artillery numbers around 4,500 in France and 1,000 in Britain. It is worth noticing that the lifetime of a naval gun exceeds fifty years, likely seventy years for a brass one (brass is bronze in real terms but British usage gives it a wrong name). France builds 400/600 guns a year, 1,000/1,200 in war time.

¤ France builds 400/600 guns a year, 1,000/1,200 in war time for its navy, all cast in iron. The main foundries are set at Ruelle, Indret, Brest, Lorient and Toulon. Britain produces 1,500/2,500 guns a year, 3,000/4,500 at war, all made of iron, at the main foundry sites of Carron, Bromley, Low Moor, Woolwich. Apart from drilling innovation, Britain is much more effective thanks to coke-fired furnaces against charcoal ones.

The Maritz' invention is promised to a great future. As everybody knows the current guns, made hollow through a clay mould in their core, lack range and accuracy owing to the rather large windage of the bore to ball diameter. Worse, they are prone to shattering owing to cast faults. The solid cast roughing escapes the latter issue.

¤ Typical windage is currently 3 to 5%, which results in 20% velocity variation, and in 60-foot dispersion at the maximum 1,000-foot battle range. Thanks to Maritz, windage can be divided by two or three, velocity dispersion be reduced to 5%, dispersion be reduced to 20-foot at a maximum battle range extended to 1,500 feet.

¤ Destruction rate is typically a gun bursting out of a hundred.

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IN RETROSPECT FROM TODAY

NOTE - on the future of the invention

The invention applies in the production of every French foundry between 1740 and 1750, and in the production of every British foundry between 1760 and 1780. Late in the adoption, Carron will improve the process and develop specific short-bore guns, the caronades, made possible thanks to accuracy improvement. This is a key factor in gun evolution.

As for destruction rate, it falls to one gun bursting out of one thousand.

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CREDIT

Jean-Étienne Liotard - portrait of Jean II Maritz - pastel, circa 1750 - © Museum of Military Heritage, Lyon