REFORMATION OF CARTOGRAPHY IN FRANCE 131 



maps of their provinces, and carried the undertaking almost to 

 completion. At the time of his death in 1784, Brittany alone 

 remained to be published. Ultimately after suspension during 

 the Revolutionary period, the v^ork was taken over by the 

 State and completed in 1818. Full details of the undertaking 

 were given by Cassini in his 'Description geometrique de la 

 France', published in 1783. 



Improvements in instruments had greatly contributed to 

 an improved standard of mapping. The divided horizontal 

 semi-circles in brass were fitted with telescopic alidades, and 

 micrometer reading allowed angles to be observed with con- 

 siderable accuracy. Beacons, and sometimes lights, were used 

 for observation marks. The topographic detail was treated 

 more summarily: though the plane table was commonly in use 

 by the *ingenieurs geographes', the body of military surveyors, 

 Cassini's men who carried out the minor triangulation sketched 

 the details by estimation or by pacing, and worked this up 

 in the office. Often they were content to indicate slopes by the 

 letters D or F ('douce' or 'forte'). 



The Cassini map when complete comprised 182 sheets 

 (88x55.5 cms.). The scale was 1 : 86,400 (i.e. 1 inch to 1.36 

 miles). In style it is based on a map of the Paris region made 

 in 1678, during the early days of the determination of the 

 meridian, by Du Vivier, and engraved by F. de la Pointe. It is 

 carefully engraved, the general effect being clean and un- 

 crowded; the great 'routes' to Paris are emphasized and named, 

 the larger towns are shown in plan, and a variety of symbols 

 mark smaller settlements, churches, wind and water mills, 

 gallows and other works of man. Forests, with their walks 

 carefully drawn, are conspicuous, as are the residences of 

 nobility and gentry, with their owners' names. Only in portray- 

 ing relief does the map fail notably. In areas of lesser elevation, 

 rivers and streams are depicted as flowing in narrow valleys with 

 the borders hatched, and isolated elevations are only occasion- 

 ally shown ; the general effect therefore is of a vast level plateau 

 dissected by canyon-like valleys. In the more rugged south 

 and south-east, the result is even less satisfactory; the terrain 

 is depicted in two or more tiers with the usual shading, and 

 long crest lines show up as narrow white bands. The land- 



