1720 - Birth of National Hydrography

The French navy ministry establishes the ‘Dépôt des cartes et plans, journaux et mémoires concernant la navigation’ which is the first official wide-purpose Hydrography Office in the world, but not the prototype of a dedicated organisation.

Its purpose looks like the one assigned to the School of Sangres (1420-60) by Prince Henry the Navigator (†1460) according to the facts and legends about his method of exploration and of collation of results. As for cartography only, there are other precedents with the Casa de India in Lisbon (from 1464) and with the Casa de Contratación in Sevilla (from 1503) which have a responsibility over the maps used by the mariners on their journeys to the crown colonies.

The French office has a responsibility on worldwide cartography and hydrography.

Compilation duty is essential, especially as the coordinates of the capes, points and coasts are flawed by lack of accuracy of the instruments. The current map of the world is terribly false actually. Nobody can imagine how false it is but everybody knows that the maps may be misleading.

A few examples will enlighten the stake :

• A few islands appear twice on the map – e.g. Saint Helena and Ascension seem to be endowed with ghost twins as they were discovered twice or more at different locations. Coordinates may be erroneous by one degree of latitude or a few degrees of longitude, which is enough to create a double.

• A few nonexistent islands also appear on the maps – e.g. Pepys Island, discovered in 1684, named after famous Samuel Pepys, supposed to be part of the South Sandwich Islands, has been untraceable since then.

• Other ones, like Iceland, too big to be confounded with another isle, are misplaced by several degrees in longitude : every mariner places it at a different place than his forerunners. It is the same case with Cape of Good Hope and Cape Horn which seem to hop from a place to the other, according to the last witness.

There is much to do.

__________

BIBLIOGRAPHY

Jean-Dominique Cassini, Romein de Hooge, Charles Pene - Le Neptune françois ou atlas nouveau des cartes marines. / Jean-Dominique Cassini, Charles Pene . Levées et gravées par ordre exprès du Roy. Pour l'usage de ses armées de mer, dans lequel on voit la description exacte de toutes les Côtes de la Mer oceane, & de la Mer Baltique, depuis la Norwege jusques au Detroit de Gibraltar... Reveu & mis en ordre par les Sieurs Pene, Cassini, & autres - Paris, 1693 - available on the Internet

Under the direction of Catherine Hofmann, Hélène Richard and Emmanuelle Vagnon - L’Âge d’Or des Cartes Marines – Paris, 2012