Timeline

Heritage classified

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Origin and history

The Cosquer Mill, also known as the Bili-Gwenn Mill, is a tidal mill located on the right bank of the Jaudy River in Troguery (Côtes-d'Armor). His existence was attested as early as 1601 in a seigneurial confession, but he was already in ruins at that time. Completely rebuilt in 1840 by the brothers Le Goaster, merchants of Tréguier, he then entered a grain shop (1841) and adopted an architecture adapted to new milling techniques using gravity. This mill, which became the Thomas mill, operated until 1991, marking the technological evolution with the installation of a turbine in 1903, a diesel engine in 1932, and electrification in 1938, while retaining tidal energy as an auxiliary source.

The site includes the mill itself, a grain store, a dyke with docking dock, and outbuildings like a stable and a dovecote. Its rectangular three-level plan, made of stoneware and shale, with granite-angle chains, reflects a careful construction. The south facade, symmetrical with a triangular pediment, and the interior machines (silos, grinding wheels, turbine) bear witness to its central role in regional flour production. Ranked a historic monument in 1999, it now houses a museum of milling techniques since the 19th century, with machinery and a potentially functional dike.

The history of the mill is marked by several influential owners: the brothers Le Goaster (reconstruction in 1840), Jean-Marie Tolguen (addition of the grain store in 1878), and Édouard Guillon, who enlarged the miller's house after 1890. In 1919, Charles Thomas and Yves Le Goff modernized the equipment, notably with a new turbine in 1921 and a diesel engine in 1932, under the supervision of engineer F. Jamet. The mill, one of the most productive in the region with 753 tons of annual flour in the 19th century, operated 264 tides a year, illustrating its economic importance until its closure in 1989.

The seamill of Bili-Gwenn appears for the first time in a declaration of inheritance of 1601 by Jean de Kerguezec, lord of Troguery. Cartographyd in 1770-1785 and then on the cadastre of 1835, its former building, described in 1798, had an outer vertical wheel and two wheels. The reconstruction of 1840 transformed its hydraulic system from a vertical wheel to a horizontal wheel powered by a courier. This mill, which was called a mill in the 19th century, symbolizes the adaptation of traditional techniques to industrial innovations, while remaining anchored in its marine environment.

Ranked as historical monuments on December 20, 1999, the Cosquer Mill protects not only the main building (outside the southeast wing of the 20th century), but also all its machinery, its grain store, the dam with its dock, and the pond retaining wall. These elements, still in a state of potential operation, offer a rare testimony of the technological evolution of tidal mills in Brittany, from their seigneurial origin to their industrialization in the 20th century.

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