Jean François Martinel was particularly concerned with the quality of relief representation in his maps. The French government had only recently adopted regulations on the appropriate depiction of relief at different scales.[i] It is clear from the mapping carried out in the course of the 1790s in Italy that cartographers were experimenting with relief depiction and gradually developing a sophisticated and highly effective relief depiction based on hachures and shadows, lit from the northwest.[ii] Martinel sought to use a combination of hachures and shadows to depict absolute height, mountain form, and the look of the countryside. This was extremely difficult to do with hachuring as inevitably an already vague sense of absolute height would be sacrificed to form. In addition, Martinel had to coordinate relief drawing by all of the members of his cartographic team, working at different times and on different sheets of the survey. If shadowing were used to indicate absolute height, depending on the judgement of the particular cartographer or on his sense of the relative height of the mountains in the area he was covering, the map would be more or less dark. The risk was that one or more maps would become impossibly dark. As indeed did occur on portions of the sheets. One strategy he employed was the pictorial depiction of terracing to suggest contours. In areas of heavy vine or olive grove cultivation this greatly enhanced the effect of his relief depiction. As part of the struggle with relief depiction, Martinel had his officers execute profiles in the regions of the battlefields. These were diagrams half way between the map and a landscape painting that succeeded in capturing relative height, absolute height and some degree of x/y coordinate location. However, they provided relatively little sense of the nature of the countryside.
[i]
On this see the Procès-verbal des conférences de la commission chargé par les différens
services publics intéressés a la perfection de la topographie, de
simplifier et de rendre uniformes les signes et les conventions en usage
dans les cartes, les plans et les dessins topographiques. In the Mémorial
topographique et militaire. Numéro cinquième publié en Septembre 1803
(fructidor an XI).
[ii] One of the most pleasing of these experiments is a little map by Louis-Albert-Ghislain baron Bacler d’Albe which was certainly inspired by de Saussure’s Vue circulaire des montagnes qu’on découvre du sommet du glacier du Buet, [plate 8 of his Voyages dans les Alpes.] In his own map, Vue circulaire des Montagnes et du Bassin en avant du village de Tende, près de la Roya et de la Grande Route de Nice à Coni, où etoit situé le parc d'Artillerie de campagne de l'armée d'Italie à la fin de l'an 2 de la République française Bacler d’Albe creates a beautiful circular profile of the view of the mountains from one location. This map is to be found at the Cartes et plan section of the Service Historique de l’armée de terre, Vincennes, under the call number L.2.789.