KEULEN, Joannes van (1654-1715). Het Rif van I[lha] de Prata. Bezuijden Sina, of Bewesten Formosa, op 20 Gr. 30 Min. N. Breete Over t'Midden. Amsterdam: 1753.
Single sheet, matted (12 6/8 x 15 7/8 inches), fine engraved chart of Pratas Island off the coast of Hong Kong in the China Sea, with contemporary handcoloring in outline, decorated with a Dutch ship, a compass rose and rhumb lines.
Pratas Island, the largest of the South China Sea Islands, is part of the Pratas Islands atoll also known as the Dongsha Islands, in the north of the South China Sea about 200 miles southeast of Hong Kong.
The map was published in Part VI of Van Keulen's Zee-Fakel (Amsterdam, 1753), the so-called secret volume of the V.O.C. atlas, which was entirely devoted to the navigation of Asian waters "where the Dutch held a prominent and envied position; this required a certain secrecy in matters of charts and sailing instructions for the Dutch pilots" [Koeman IV, p. 364].
Johannes van Keulen established himself in Amsterdam in 1678 and in 1680 he obtained a privilege from the States General of Holland and West Friesland allowing him to print and publish maritime atlases and shipping guides. This privilege, which protected against the illegal copying of printed material, was especially important for the cartographer's atlases, which were produced with extensive initial costs. Van Keulen named his firm "In de Gekroonde Lootsman" (In the Crowned Pilot), and began collaborating with cartographers Claes Janz Vooght and Johannes van Luyken. The firm would go on to become one of the most successful publishing firms in Amsterdam; and produce "the largest and finest marine atlases in Holland" (Koeman).
Van Keulen's first atlas was his "Zee Atlas" with about 40 charts. "The culmination in the development of Dutch pilot books was reached with the publication of "De Nieuwe Groote Lichtende Zee-Fackel…" in 1681...The work was immediately recognized as superior to anything else on the market and enjoyed a considerable reputation for accuracy and detail" (Martin & Martin, 11).
On the death of Joannes in 1704 the firm passed to his son, then his grandson, and on the death of Cornelis Buys van Keulen the name of the firm "was altered after much palaver into Gerard Hulsst van Keulen. The surviving son conducted the publishing business with more ambition than before. A considerable number of books appeared in the period 1778-1801. Greater activity was developed in the cartographic branch and new issues of the "Zee-Fakkel" again saw the light" (Koeman page IV 279). Koeman Van Keulen IV pp. 382-3 (267-8).