In 1820, Pierre Coëtanlem completed his 8,334 page Breton-French dictionary. He was a great admirer of the science of etymology and reflected the prejudices of the scholars of his day by placing more value on written than oral sources. Isolated in his Manoir de Trogriffon, he undertook an extensive comparative study of the works in his library to compile this dictionary. According to Falc’hun, however, its linguistic value was not as great as its volume might suggest: ‘It lies in the rare details that the author almost inadvertently gives us on the Breton of Morlaix.’ These ‘rare details’ include dialectal data that provide information on the coastal geolinguistics between the Penzé and the Rivière de Morlaix around the turn of the 19th century, including the following Breton maritime terms: sirga ‘to haul, tow’, evôr ‘anchor’, ar wern-valouin ‘the bowsprit’, lewia ‘to steer a ship’, gôbar ‘gabarre’ (flat-bottomed barge) and aber ‘estuary’.