Very interesting. Thank you. I need to learn more about Cassini.
The map also appears to be consistent with a flat earth.
‘Experimental evidence supporting this idea [that the Earth is shaped like an orange] came in 1672 as a result of a French expedition to Guiana. The explorer [Jean Richer (1630-96)] found that a pendulum clock that kept good time in Paris lost 2½ minutes a day at Cayenne near the Equator. At that time no one knew how to interpret the observation; but Newton’s theory that gravity must be larger at the poles (because of its closer proximity to the Earth’s centre) than the Equator was a logical explanation. It is possible to determine whether or not the Earth is an oblate spheroid by measuring the length of an arc corresponding to a geodetic latitude differences at two places along the meridian (the ellipse passing through the Poles) at different latitudes, which means at different distances from the Equator.’  Encyclopaedia Britannica, chapter: Earth, p.535.
King Louis XIV of France approved Cassini’s last great expedition. With the aid of his son Jacques Cassini and others, he measured the arc of meridian from Paris north to Dunkirk and south to the boundary of Spain, and, in addition, he conducted various associated geodesic and astronomical operations that were reported to the Academy. Cassini knew that it would be virtually impossible to measure every kilometre of meridian from Pole to Pole at the time. At best, a partial measurement would confirm a probable shape of the Earth. Consequently they decided to measure where it was most convenient, restricting their efforts to Europe in the northern hemisphere.
The results showed the length of a meridian degree north of Paris was 111,017 meters or 265 metres shorter than one south of Paris (111,282 meters). This suggested that if this trend occurred in the southern hemisphere, the Earth has to be a prolate spheroid, not flattened at the poles as Newton proposed, [or flat] but the opposite, slightly pointed, with the equatorial axis shorter than the polar axis, that is, kind of egg-shaped. In 1720, Cassini published his findings.