In the years 1771-1772 the French government sent a scientific expedition to the North Atlantic. It was led by Verdun de la Crenne, and he was accompanied by a group of scientists. Their commission was to explore the ocean, the coasts, and the islands on their route. They were to correct errors on existing charts and test various ways of measuring latitude and longitude. They reached Iceland in the Western Fiords and remained for nearly three weeks in Patreksfjördur and made numerous observations, measured the latitude and longitude, and took some soundings. Based on these measurements they moved the country three and a half degrees eastwards, though without disturbing the longitude of the east coast to any extent. This doubtful result was then the basis of the representation of Iceland on the French chart of the North Atlantic.
Although the French made some noteworthy observations and measurements, they were all restricted to a limited area on about one third of the coast. In spite of some good points, their chart was much less accurate than those already in existence. They had particular difficulty in fitting in all of the south and north coasts within the narrow limits imposed by their estimate of the breadth of the country from east to west. But those involved were distinguished men, and so it is not surprising if others followed their example.
The two versions, Knoff and Verdun de la Crenne, were for a long time rivals for acceptance, and for a while the latter had the best of it.