22) Two developments were crucial: indirectly, the invention of the contour line (curved lines of equivalent elevation first used to show the overall form of landmasses on a French map of (1791) and, directly, Johann Georg Lehmann's 1799 invention of shadow-hachures
, an arrangement of hachures
that emphasized the "transition from level ground to steep gradients.
1915, in a version with hachures
held in the Dickson offices of the ACT Planning and Land Authority.
I anticipated commentary on the mixture of point, line and area symbols, on the selection of colours and hachures
that mimic perceptions, on the evolution of choropleths and other thematic techniques, and even on the origins of the idea of making interpretive statements about collective social behaviour in mapped form.
The presentation of the maps harks back to the original printed maps of the period, with their distinctive watercolour-like tones, hachures
and lettering, and their fascinating historical and geological information.
Relief is shown by hachure
with towns, cities, and major topographical features identified.