CARTE DE L'ARCHIPEL AU NORD DE L'ISLE DE FRANCE. . . - REUNION,MAURITIUS,SEYCHELLES,DIEGO GARCIA.

A rare, large, and fine antique naval chart, depicting the Indian Ocean from as low as Mauritius to the southernmost Maldives islands, with an inset map of the Seychelles archipelago and a key to the surveys depicted on the map. It contains the routes of 24 surveys of this area from 1743 to 1775, each marked with a letter.
Jacques-Raymond de Grenier (1736?1803) was a naval officer and hydrographer, best known for his maps of the Indian Ocean. De Grenier spent the years 1768?1769 and 1772?1776 exploring and mapping the many islands in the Indian Ocean, particularly those where the French had colonial possessions and interests.
He recounted his discoveries in the work entitled 'Mémoires de la Campagne de Découverte dans les Mers des Indes', published in 1770. During his research on the prevailing currents and winds during the southwest and northeast monsoons in The Indian Ocean, de Grenier discovered more direct, and therefore faster, routes to and from the French colonial possessions in India, notably the Coromandel coast and a passage to the Strait of Malacca, thus reducing the distance of these voyages to 'approximately 3,200 kilometers.

From: 'Hydrographie Françoise', vol. 2, 95 C. [numbered by hand.], this map was included in later editions by Bellin.

The Dépôt de la Marine, known more formally as the Dépôt des cartes et plans de la Marine, was the central charting institution of France. The centralization of hydrography in France began in earnest when Jean-Baptiste Colbert became First Minister of France in 1661. Under his watch, the first Royal School of Hydrography began operating, as did the first survey of France’s coasts (1670-1689). In 1680, Colbert consolidated various collections of charts and memoirs into a single assemblage, forming the core of sources for what would become the Dépôt.

The Dépôt itself began as the central deposit of charts for the French Navy. In 1720, the Navy consolidated its collection with those government materials covering the colonies, creating a single large repository of navigation. By 1737, the Dépôt was creating its own original charts and, from 1750, they participated in scientific expeditions to determine the accurate calculation of longitude.

In 1773, the Dépôt received a monopoly over the composition, production, and distribution of navigational materials, solidifying their place as the main producer of geographic knowledge in France. Dépôt approved charts were distributed to official warehouses in port cities and sold by authorized merchants. The charts were of the highest quality, as many of France’s premier mapmakers worked at the Dépôt in the eighteenth century, including Philippe Bauche, Jacques-Nicolas Bellin, Rigobert Bonne, Jean Nicolas Buache, and Charles-François Beautemps-Beaupré.

Reference: https://gallica.bnf.fr/ark:/12148/btv1b531428047