Early last year, whilst fathoming the contours of this project, I began consulting that fount of all knowledge and (mis)information: the internet. Here were numerous inventors of the line: should I include all isolines? (no – more on them later), isobaths (yes).
The Dutch have been adding depth lines to rivers since 1584, though Wikipedia only gave me Cruquius with a date of 1727. It is likely neither the French nor Italians knew of the Dutch maps while ‘inventing’ isobaths to plot (among other water courses) the Gulf de Lion around 1706 and the Channel in 1737. The picture becomes murkier once we ‘climb out of the sea’.
Straight from Wiki (though the link now seems to have disappeared): “Such lines were used to describe a land surface (contour lines) in a map of the Duchy of Modena and Reggio by Domenico Vandelli in 1746”. The Via Vandelli still exists but finding out about the man wasn’t helped by there being a more famous Portuguese Domenico Vandelli; a contemporary also working in Italy (and all over the internet for being good at botany).There was also Marcellin Du Carla, a French geographer who wrote extensively about contour lines and with publisher / mapmaker Dupain-Triel created maps devoted to extolling contour lines as a way of understanding land formation (beginning in the 1770s). So Hutton (1775 – 78) was still in contention to beat the French into second place.
Last summer I decided a neat – and poetic – way forward would be to limit research to a river, a road and a mountain:
Cruquius: Netherlands, river (Merwede, isobaths), 1727
Vandelli: Italy, road (Via Vandelli, contours), 1746
Hutton: Britain, mountain (Schiehallion, contours), 1777
Simple? No? No.