The Swiss cartography dispute: opinions differed about the shadow

Albert Heim (1849–1937) was a real high flyer. In 1873, at the age of 24, he was appointed professor of geology Polytechnic University of Zurich three years later he also worked in the same position at the University of Zurich. With his research into the formation of the Alps, the double professor of geology made a name for himself far beyond the country’s borders.

Heim’s activities were not limited to geology. When something was important to him, he defended his position with great tenacity. Albert Heim was a staunch supporter of cremation, which was anything but common in the 19th century – it was not opened until 1889 Sihlfeld Cemetery Switzerland’s first crematorium in Zurich. In addition, the geologist called for equal rights for women and was involved in the temperance movement, which advocated abstinence from alcohol.

Less well known are Heim’s passionate interventions in the world of Swiss cartography. In 1927, the then 78-year-old geologist sharply criticized the two sets of state maps of Switzerland. According to Heim, the Dufour and Siegfried maps, as the official maps of Switzerland were called at the time, contained a “lie” that was “nature’s fist in the face.” The point of contention was the fact that the imaginary light source, which provided light and shadow in the map image and thus gave an immediate three-dimensional impression, came from the northwest in those map works.

Albert Heim was an outspoken opponent of the so-called Northwestern illumination of maps, which became increasingly common worldwide in the 19th and 20th centuries. According to the geologist, this was at odds with reality, as the sun in Switzerland usually shines from the south.

Albert Heim therefore saw the northwest lighting as a “mistake from the past” that needed to be corrected. The map image must correspond to the natural conditions: as the producer of the official maps of Switzerland, this must also be done Topography of the federal state (Today: swisstopo) switch to enlightenment from the south and take “the great step from lost convention to nature”. Heim was not entirely alone in this demand: Emil Klöti, State Councilor of Zurich (1877–1963) also addressed state topography in the 1930s with dedicated advocacy for southern enlightenment.

Today, the northwest illumination of maps is something the human eye can take for granted. The introduction of southern relief would lead to misinterpretations: valley floors would be mistaken for mountain ridges and mountain ridges would be misinterpreted as valley floors. But this visual habit is not natural, but rather learned. Why did northwest lighting become the dominant standard in map design?

Presented here are two explanations advanced in the Enlightenment debate of the late 1920s. Albert Heim himself referred to the working method of the people who drew the maps and engraved them on copper plates: “The cartographer who draws with his right hand needs the light from the top left, so that his draftsman’s hand does not overshadow his work.” Because draftsmen and engravers often turned their plates or copper plates back and forth during their work, this derivation is only partially convincing.

Responding to Heim’s 1929 polemic, Zurich cartography professor Eduard Imhof (1895–1986) emphasized that the enlightenment of the left was due to the fact that people in Europe write from left to right and the majority of people draw with the right. hand. For this reason, the incidence of light was already designed from left to right on medieval and early modern maps.

Initially this had nothing to do with the direction of real sunshine: on maps from the Middle Ages and early modern period, east was often on the left and south on top; there was no set standard. It was only when north-facing maps became the standard in the 19th century that lighting from the top left also became lighting from the northwest.

The dispute over the direction of illumination was ultimately based on different ideas about what a map actually is. For Albert Heim, a topographical map must represent the conditions in nature – and therefore also the light in the area – as realistically as possible. The cartographers of state topography, on the other hand, saw their maps as a tool intended to enable the clearest and most intuitive orientation in space possible. For them, the light on the map was a stylistic device to make ascents and descents easier to understand – it had nothing to do with real sunshine.

Despite his persistence, Albert Heim was adamant about the illumination problem – to this day, not only Swiss maps, but also most foreign maps from the northwest are illuminated. Ultimately, his arguments had no chance against viewing habits that had developed over the centuries. Continuity is an important currency in cartography; A change to the already established northwest light direction would have caused too much confusion almost 100 years ago.