throughout Europe for decades.
The Map title (shown at the top of this page) reads:
The map was scanned, entered into GRASS, georeferenced, and entered into the GIS system as a data layer like any other. This map is quite general in its spatial accuracy, but it is the oldest map yet located that covers the research area.
Close-up views of the 1659 map
Several enlargements of the 1695 map, showing the Arroux river, towns, forests, roads, and structures. The walled town of Issey L'Eveque at left still remains intact, and Mt. Dardon is just above it and to the right. Each structure icon has a specific meaning, as show in the Cassini map below.
1759 Cassini Maps
Statue of Cassini 1 at the Louvre Courtyard in Paris
We are very fortunate to have available to us two superbly accurate reproductions of maps of the region that were produced in 1759. The famous Cassini triangulation surveys of France were conducted by four generations of the Cassini family in the late 1600's to mid 1700's. In 1672 Jean Dominique Cassini, (Cassini I) Royal Astronomer of the Paris Observatory, began to consider new ways to produce more accurate maps through triangulation, similar to the techniques used by astronomers to measure the size of the planets and the Sun. Better maps were needed to determine the accurate distance between observatories on the Earth more precisely, in order to conduct simultanious measurements of the planets from different observatories. He and his son, Jacques Cassini (Cassini II) produced the map at right, the first accurate survey of an entire nation, in 1744. They also mapped an accurate baseline between the Paris Observatory and Greenwich, England to support concurrent celestial observations and measurements.
In 1747 Louis XV asked Ceasar-Francois Cassini (Cassini III) to create an even more precise national map of France. This was completed by his son Jacques Dominique Cassini (Cassini IV), with 180 maps covering all of France at a scale of 1:86,400. These 180 'cartes de l'Academie' maps of France were a superb product, far more accurate and detailed than any previous maps. They were published from 1798 through 1812. Reproductions of these maps are available for all of France from the Institut Geographique National in Paris.
These historic maps are extremely detailed and spatially accurate, much more so than the older Sanson map we possess created 100 years before. The Cassini maps provide us with the oldest, detailed, reasonably accurate record of the location of roads, bridges, towns, streams, and villages of the area. It also shows information about the current vegetation and land-cover of the area. The maps contain an astounding level of detail. This is a particularly fortunate period for obtaining accurate cartography of the region, as it is before the French Revolution. The map scale of is 1:86,400.
The map scale that was used for these maps then was in the old units of measurement:
1 ligne=100 toise.
One toise (English fathom) was equal to 6 pieds (English feet), one pied (English foot) was equal to 12 pouces (English inches), and one pouce was equal to 12 lignes (English lines). So one ligne (1/12 of an inch) on the map was equal to 100 fathoms (600 feet) on the ground...thus a modern scale, or more properly, the repesentative fraction, of these maps is 1:86,400 (or 1 : 6x12x12x100).
A 'toise' was a traditional French unit of distance comparable to the British fathom (or 6 feet). Like the fathom, the toise originally represented the distance between the fingertips of a man with outstretched arms. Introduced by Charlemagne in 790, the toise is such an ancient unit that the French 'toiser' has become a verb meaning "to measure" or "to size up."
The toise equals six pieds (French feet). The 'pied' was the traditional French foot. Pieds of various lengths were used in France, but the one best remembered now is the royal foot (pied de roi), called the Paris foot in English and the foot (French measure) in Canadian law. The pied de roi equals about 32.48 centimeters or 12.79 inches; the official Canadian definition is 