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PASSAGE TO INDIA / THEMATIC MAPPING / INDIAN OCEAN / HYDROLOGY / IMPORTANT ENLIGHTENMENT CARTOGRAPHY: Carte du Sisteme des Courants des Mers de l’Inde dans le Tems de la Mousson du N.E. au N. de la Ligne. Publiée par le Vicomte Grenier.



Highly Important and Rare – a great monument of Enlightenment Era thematic cartography – Vicomte Grenier’s of sea chart showcasing his new, faster sailing routes across the Indian Ocean, discoveries which revolutionized European-Asian transportation and geopolitics.

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[A Chart of the System of Currents in the Indian Ocean during the Time of the Northeast Monsoon to the Northward of the Equator].


Copper-engraved sea chart on thick laid paper, Southwest Monsoon chart watermarked ‘De La Forie 1788’ (Very Good, strong engraving impression, light toning, wide side margins, tiny repaired tears and holles in the upper middle part), sheet: 47.5 x 64 cm (18.5 x 25 inches), platemark: 46 x 50 cm (18 x 19.5 inches).


The chart embraces the bulk of the Indian Ocean, from Mozambique to Present here is map by Jacques Raymond Giron de Grenier’s rare sea chart, which showcases the new, dramatically faster sailing routes across the Indian Ocean he personally discovered and mapped during several expeditions in the 1760s and ‘70s.  The first chart details Grenier’s new routes for sailing from the direction of Europe across the Indian Ocean to India and the Straits of Malacca during the Northeast (Winter) Monsoon, while the second chart details his new routes for sailing to the same destinations during the Southwest (Summer) Monsoon.  In large part due the publication of the present charts, Grenier’s routes were used by both French and other European mariners, so reducing shipping times to India and the Far East by several weeks, with profound consequences to global economic, political and military affairs.  The charts are thus amongst the most impressive and consequential works of thematic cartography of the Enlightenment Era.


the entrance of the Strait of Malacca.  India occupies the pride of place, labelled as the ‘Presqu’ile de l’Inde’, featuring its coastlines, ‘Cote de Malabar’ and ‘Cote de Coromandel’, and ‘Pondicheri’ (Pondicherry), the capital of French India.  Other places of note include the ‘I. de France’ (Mauritius), the French colony that was Grenier’s base of operations; ‘I. de Boubon’ (Réunion); Madagascar; ‘I. de Seichelles’ (the Seychelles), a critical waypoint along Grenier’s new routes; the Maldives; and the ‘Détroit de Malaca’ (Strait of Malacca), the gateway to the Pacific and the Far East.  Grenier represents the directions of the ocean currents with arrows, while shuttlecock-like forms represent the directions of the winds.  The charts acknowledge that the Summer and Winter Monsoons variously dominate the navigation of the Indian Ocean during most of the year, and so the skilled use (or avoidance) of the monsoons’ powerful ocean and wind currents will determine the course and speed of travel.


Carte du Sisteme des Courants des Mers de l’Inde dans le Tems de la Mousson du N.E. au N. de la Ligne, represents the Indian Ocean during the period of the Summer, or Northeast Monsoon, during which, from roughly September to March, strong winds sweep down from the northeast from the Himalayas across the Indian Subcontinent and the Indian Ocean down to the Equator.  As shown on the chart, the shuttlecocks show the wind directions above the Equator to come from a north-easterly direction, while the ocean currents roughly follow the same trajectoty.  Grenier notes the traditional route for sailing from Europe to India during this time of year, marked as ‘Suite de l’Ancienne Route por aller aux Indes’, which had ships swing from the Cape of Good Hope way out into the middle of the Indian Ocean, in order the avoid the brunt of the Monsoon’s force.  In a dramatic improvement, Grenier’s newly-discovered alternative routes, marked here as ‘Route du Chr. Grenier’, had vessels sail up past Madagascar’s east coast and near the Mascarene Islands, and almost due north to a point just east of the Seychelles and a touch below the Equator, whereupon ships should swing east to either curl up towards India or continue due to the Strait of Malacca.  Alternatively, for the Red Sea or Persian Gulf, one could bow to the northwest from the same point near the Seychelles.  In many cases, following Grenier’s new passage to India could result in savings of 3,200 km against the traditional route!  It also brought vessels closer to landfall en route, avoiding difficult months-long periods far from land with not opportunities to revictual.


It must be noted that Grenier made provisions for both the Winter and Summer routes to be modified slightly, such that ships could revictual at the Seychelles, without losing much time, should they so desire


The present example is of the second (of 2) state of the chart.  The first states of the charts were published by Jean Lattré as separately-issued sheets shortly after Grenier returned to France from his second period of exploration in the Indian Ocean.  While dated ‘1776’, they were likely printed in 1777, as Grenier arrived in Paris in December 1776, making it unlikely that the plates were rushed out by the end of that year. 

The present second state of the chart are identical to the first, save for the additions of the numbers 95(a) in the upper right corner.  It seems that Lattré’s original plates were retained by the Dépôt des cartes et plans de la Marine, the French Navy’s hydrographic office.  Between 1776 and 1802, the Dépôt issued composite atlases featuring the “Greatest Hits” of French marine cartography from the Enlightenment Era, entitled, Hydrographie françoise. Recueil des cartes marines générales et particulières dressées au Dépôt des cartes, plans et journaux, par ordre des ministres de la Marine.  The atlas featured charts issued from their original plates, only adding numbers in the upper-right corners, like the present charts.  The Hydrographie Françoise was issued in a variety of collations, which sometimes did or did not feature the present charts. 


A Note on Rarity

All issues of Grenier’s charts of the Indian Ocean routes are very rare.  We can only trace examples of the charts appearing separately at the Bibliothèque nationale de France (being 2 pairs of the first state and 1 pair of the present second state).  Moreover, we can trace only 4 institutional examples relevant Hydrographie Françoise atlas featuring the second states of the charts, being held by the Bibliothèque nationale de France; Muséum national d’histoire naturelle (Paris); Biblioteca Nacional de España; and the National Library of Israel.  Moreover, the charts are extremely rare on the market; we can trace only a single sales record for only the Northeast Monsoon chart from the last 30 years.

Le Chevalier Grenier and the New, Fast Passage to India

Traditionally, as discussed, the preferred shipping routes from Europe to India and the Far East involved making long detours in the Indian Ocean from what would be more direct routes, to avoid the brunt of the Monsoons and to take advantage of favourable currents in the margins.  While these routes were relatively reliable, they had severe drawbacks, in that they were very long and often took vessels thousands of kilometres away from safe harbours, meaning that ships would have to be out at sea for weeks without being able to re-victual, or make emergency stops. 

For many years, French ship captains had reported that a much shorter route to the East Indies existed by sailing from South Africa, up past Madagascar and then past the Seychelles, and then over to India.  However, these reports, while considered credible, described the route imprecisely and the much of the island and reef-strewn tract of the Indian Ocean in question had never been charted to a degree of reliable accuracy.  Moreover, the critical affects of the Southwest (Summer) and Northeast (Winter) Monsoons in those waters were not well understood.  Attempting to blindly find and follow this route promised to be dangerous.

Bertrand-François Mahé de La Bourdonnais, the brilliant and enterprising Governor of Île de France (Mauritius), who served from 1735 to 1746, endeavoured to define and exploit the route, yet greater events overtook him before he could see things through.

In the wake of France’s loss to Britain during the global Seven Years’ War (1756-63), which broke out into the Third Carnatic War in India, she was desperate to find an edge to restore her political and economic competitiveness in Asia.  Some of the more prescient figures in the French government and navy came to consider the opening of a new, faster sea route to India as a possible ‘trump card’.

Enter Jacques Raymond de Giron de Grenier (1736 – 1803), known as Le Chevalier Grenier (later Vicomte), a skilled naval commander, who hailed from an old Bordeaux noble family that boasted centuries of distinguished service to the French Crown.  Grenier was born at St. Pierre, Martinique and joined the navy at a young age.  During the Seven Years’ War, he served with great skill and valour, in both France and the West Indies, in what was a disastrous conflict for France.  An unusually gifted cartographer and mariner, Grenier was eager for a grand new challenge, and so he came to the attention of his superiors as the man who could open the new passage to India. 

In 1767, César Gabriel de Choiseul, duc de Praslin, the French Minister for the Navy & Colonies, ordered a mission led by the Chevalier Grenier to be outfitted for the East Indies to find and chart new, fast routes to India.  Grenier’s party left Lorient, Brittany, on November 29, 1767, aboard l’Heure du Berger, arriving at the Île de France (Mauritius), on July 27, 1768, after a much longer than expected voyage.  As the first charting of the new route to India was to occur during the favourable conditions of the Southwest Monsoon (which would end in just over a month), it was considered too late in the season for Grenier to proceed with his principal endeavour.  Consequently, his activities for the next several months would dovetail into the priorities of the Île de France’s governor, which were fortunately closely related to the overall mission.

Pierre Poivre, the Governor of the Île de France (Mauritius), and the chief French official in charge of French interests in the southwestern Indian Ocean, possessed, like his predecessor Mahé de La Bourdonnais, bold ambitions.  He wanted to expand France’s footprint in East Africa and across the islands that dotted the Indian Ocean.  First, he wanted to re-establish a permanent French settlement on Madagascar.  While French agents and merchants were already the dominant European presence on the island, the potential for far more trade was held back by the lack of a permanent base on the island (an earlier French settlement at Fort Dauphin lasted only between 1642 and 1674).  Second, Poivre wanted to establish the hitherto uninhabited Seychelles as a French colony.  While accomplishing these goals would grow the regional French colonial economy, it wold also serve to secure the fast shipping route to India which would sail past islands under French control.

From August 1768 to January 1769, Grenier, aboard the l’Heure du Berger, explored and charted the east coast of Madagascar, meeting tribal chiefs and merchants to discover the best locations for building a French settlement on the island.  Upon his return to Île de France, he produced a detailed report, accompanied by a fine manuscript chart, which was much valued by Governor Poivre and the Duc de Praslin.

On Île de France, Grenier spent months preparing for a grand mission with two key objectives.  First, was the discovery and mapping the fast passage to India.  Second, was to visit, map and analyse the Seychelles with respect to forming a plan to colonizing the islands.

Grenier was to be partnered with the esteemed scientist Alexis-Marie de Rochon (1741 – 1817), popularly known as the Abbé Rochon.  In theory, Rochon’s presence would be a major asset to the mission, but as it turned out Grenier and Rochon immediately took to hating each other the moment they met, and their relationship only deteriorated from there on!

The mission left the Île de France aboard the l’Heure du Berger on May 30, 1769, just as the Southwest Monsoon was gearing up.  Grenier was to take the lead in the actual hydrological work, while Rochon was to conduct all the latitudinal and longitudinal readings, calculated from astronomical observations, critical data that underpinned the accuracy of the entire venture. 

The l’Heure du Berger quickly caught the fast route towards India, following the favourable currents and winds, sailing past Saint-Brandon Island, over the Nazareth Bank and then by Saya de Malha Bank, before arriving at the Seychelles on June 14, 1769.  However, while Rochon reluctantly supplied Grenier with the geodetic readings, the relationship between the two men had deteriorated to the point where they refused to communicate with each other, let along cooperate. 

Grenier and Rochon mapped and assessed the Seychelles separately, refusing to share information with one another.  Departing the Seychelles, the l’Heure du Berger regained the fast route, sailing to the Maldives, before anchoring off India’s Malabar Coast on July 29.  The mission then proceeded to Pondicherry, the capital of the French India, on the Coromandel Coast, arriving on August 6, 1769.  Especially if one accounts for their stops, the l’Heure du Berger made amazingly fast time between the Île de France and India. 

After leaving Pondicherry, Grenier was eager to test the extension of the fast route from India to the entrance of the Strait of Malacca, the gateway to East Asia and the Pacific. The mission arrived there on September 9, before making the return trip back to Île de France, via Diego Garcia, all the while measuring the winds and currents.  The l’Heure du Berger arrived back in Île de France on October 6, 1769, the entire circle tour having been remarkably swift.  Grenier was thus the first person to scientifically record and the fast passage to India.

Grenier returned to France in 1770, and as soon as he set foot on land immediately had his account of the Trans-Indian Ocean tour published as Mémoires de la campagne de découvertes dans les mers des Indes (Brest, 1770).  This extremely rare pamphlet contained the first scientific and accurate description of the fast shipping route to India.

Over the next couple years, Grenier produced several amazing maps, including a chart of the currents in the Indian Ocean which is a rudimentary version of the present charts.  This map was included in the second edition of Grenier’s Mémoires (1772).

Grenier also produced a stellar large-format sea chart depicting the routes of various named vessels from the Île de France to India, a work which would have informed the present charts, Carte réduite de l’archipel de l’Inde compris antre les Isles de France de Madagascar et la Ligne Equinoctiale, contenant une partie de la Presqu’isle de l’Inde Dressée au Dépôt des Cartes et Journeaux de la Marine et une partie de l’Isle de Madagascar Corrigée depuis le Cap d’Embre jusqu’à Tamatave par divers Marines et depuis Tamatave jusqu’à Mananzary (Paris, early 1770s).

Louis XV’s ministers were highly impressed with Grenier’s work, considering the discovery of the fast passage to India to be perhaps a transformational benefit to French commerce and political fortunes in the East Indies.  Grenier was promoted to become a First Lieutenant in the Navy and feted with honour in Paris.

As for the Seychelles, Grenier and Rochon submitted separate reports; however, both assessments held the islands to be ideal for permanent settlement and the establishment of spice and other plantations.  Due to their recommendations, from 1770 onwards, French setters arrived on the islands, along with over 10,000 nutmeg and clove seeds.  The plantations proved to be successful, and the Seychelles developed into a small, but thriving, colony, along Grenier’s new shipping routes across the Indian Ocean.  The islands also became a haunt for French privateers that prayed on British shipping, resulting in serious consequences.

Rochon tried to steal Grenier’s thunder by submitting a stunningly beautiful map of the Seychelles to the Duc de Praslin, the “Carte plate des isles Seychelles, Praslin, Silhouette, et autres qui leur sont adjacentes situées” (1769).

However, Grenier later submitted a far less flashy, yet more accurate, map which was subsequently published as the Carte des iles Seychelles et des Amirantes (Paris: Lattré, 1776).  Please see a link to our 1803 British edition of Grenier’s chart of the Seychelles, which is faithful to the original:


In 1772, with the enthusiastic backing of the government, Grenier returned to the Indian Ocean to continue his hydrological research.  Based, once again, at the Île de France, beginning in October 1772, he set out to find the fastest shipping route to India during the Winter (Northeast) Monsoon.  He took an indirect route to the Seychelles and then cut across to Pondicherry, before returning to Île de France.

The following season, Grenier embarked upon a grander tour to test the new route going through and beyond the Straits of Malacca.  In July 1773, he left Île de France and sailed for Pondicherry, before continuing through the Strait all the way to Manila, Phillipines.  He returned to Île de France in April 1774.

In February 1775, Grenier retested the Winter Monsoon, sailing to the Seychelles and then Pondicherry, before returning all the way back to France at the end of November 1776.

On Grenier’s return home, armed with a vast wealth of scientifically-tested data on both the new, fast routes to India and beyond during both the Summer and Winter Monsoons, Grenier produced the present pair of charts, which remained his most mature and sophisticated graphic renderings of his hydrological discoveries.

Grenier’s discovery of new, fast passages to India that could be used during both Monsoon seasons was hailed by the French maritime community as a revolutionary development.  It became a seminal part of the sailing instructions issued to all French merchant and naval captains sailing to India and beyond.  This dramatically reduced shipping times, not to mention saving many lives and vast sums of money. 

Importantly, the French naval hero Admiral comte Pierre André de Suffren credited Grenier’s routes for the navigation of his fleet across the Indian Ocean in 1781, the speedy progress of which is thought to have saved both Pondicherry and Cape Town, South Africa (a Dutch city, allied to France) from falling into British hands.

While the decision to publish Grenier’s discoveries allowed them to widely benefit the French marine community, it came with unintended consequences.

The leading London chart makers of Robert Sayer & Jonathan Bennett translated and republished both of Grenier’s present charts as part of their sea atlas of African and Asian navigation, The Oriental Pilot (London, 1778).  This ensured that Grenier’s work reached the attention of British naval and merchant captains.  Britain, which had traditionally neglected the quadrant of the Indian ocean running from Madagascar and the Mascarene Island up to the Seychelles, suddenly became quite interested in the area. 

Brutish vessels began to regularly use Grenier’s routes to India, passing close to French-held islands, increasing tensions between the rival states.  During the French Revolutionary Wars (1792 – 1802), whereupon Britain and France came into conflict, French-backed privateers based in the Seychelles attacked British shipping.  In response, in 1794, a British expedition seized the Seychelles.  Britain would permanently retain the islands. 

During the Napoleonic Wars, in 1810, Britain conquered both the Île de France (Mauritius) and (Réunion).  After the war, Britain returned Réunion to France, but permanently retained Mauritius, which became their main base in the southwestern Indian Ocean.  From there, between 1816 to 1835, Britain staged a temporarily successful design to make Madagascar a client state.

While France would later regain its footing in the Indian Ocean, assuming suzerainty over Madagascar in the late 1850s, there is no doubt that the dissemination of Grenier’s discoveries fueled Britain’s decades-long powerplay in the region.

As for Grenier, he inherited the noble title of ‘Vicomte’ in 1776 and served with great valour during the American Revolutionary War (1775-83), in both America and the West Indies, notably playing a key role in the recapture of the island of Saint-Barthélemy.  Following the conflict, he was promoted to the rank of Rear Admiral, before retiring from active service in 1786.  His last major publication was a treatise on naval battle tactics, L’Art de la guerre sur mer, ou Tactique navale, assujettie à de nouveaux principes et à un nouvel ordre de bataille (Paris, 1787).

Grenier’s hydrological discoveries had an enduring legacy in that his fast passages to India came to benefit mariners of all flags for generations, bringing the World closer together.  Grenier’s routes remained the gold standard for European-East Indies navigation until the opening of the Suez Canal in 1869.

References: Northeast Monsoon Chart: Bibliothèque nationale de France, département Cartes et plans, GE SH 18 PF 1 TER DIV 9 P 2 D; Southwest Monsoon Map: Bibliothèque nationale de France, département Cartes et plans, GE D-12867. Cf. Manonmani Filliozat, ‘J.B. D’Après de Mannevillette et la Cartographie de la Nouvelle Route des Indes’, CFC, no. 175 (Mars 2003), pp. 6-16; Jean-Paul Morel, ‘Le chevalier Grenier et Alexis Rochon: la nouvelle route des Indes. (30 mai – 6 octobre 1769)’, [online article, October 2012], link:http://www.pierre-poivre.fr/Grenier-la-route-des-Indes.pdf

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