This post is part of a blog series on historical data vis titled “Data Trails. Snapshots from the history of data visualisation” and originally appeared over at my friends’ from Idalab, a Berlin-based specialist on data science and machine learning.
There is a very basic joy in roaming through atlases and in looking at maps. Atlases are rich collections of places, and if there is one thing they can do it is making you travel around the world, to places near and far. Cartography – an age-old discipline combining science and art – has created a unique way of looking at our planet, of flying over continuous landscapes and endless oceans. The 19th century was a golden age of atlases. Beautiful pieces for the educated household were printed in many different countries. Many of them feature one very special type of map: the comparative tableau showing the longest rivers and highest mountains of the world.
This type of maps presents you with a mind-blowing experience of looking at the whole world at once. Instead of depicting a given landscape according to the conventions of cartography, these maps present the world’s biggest mountains and the longest rivers in one fictional space – i.e. next to each other. Many different variations of this type of map have been created through the 19th century, and it is fascinating how the format integrates diagram, map and panorama view in one visual set-up. Mapmakers have spared no effort to arrange the geographic elements in ornate layouts – sometimes in a circle, sometimes in a diagonal design, sometimes in a diagram. Here is one alluring example printed in London in 1836, and it perfectly exemplifies what I love about these: they look like a map, but they are not. They defy our expectation to look at a unified representation of geographical space, and instead they present us with an impossible accumulation of rivers and mountains.
Look at the neatly ordered rivers! Their arrangement forms a beautiful halo around the centrepiece of this map: a virtual mountain, which absorbs in its enormous belly the highest individual peaks of the world. The rivers meander nicely from their respective sources surrounding the mountain towards their estuaries. They finally flow into a non-descript universal sea at the top, and it is but one curiosity arising from this layout that the rivers flow upwards. Another one is that when you order rivers by their length instead of their geographical position you create new neighbours. So for instance you get to have the Mississippi and the Yangtze sitting next to each other, shrinking the real-world distance from New Orleans to Nanjing to just a stone’s throw.
For centuries now, maps have been based on the conventional grid of longitude and latitude. This coordinate system for representating terrestrial space is deeply engrained in our brains and it is invoked whenever we look at a map (this is also why cartograms – which represent a statistical variable by blowing up or shrinking the respective map space are so difficult to wrap your head around). Our comparative tableaus dissolve this cartographic space – they break off rivers and mountains from their natural habitat and place them next to each other for comparison.
What I particularly like are the fictions which arise from this logic of arrangement. Defying scientific standards, these fictions are readily embraced and beautifully executed. For instance, our monolithic mountain rises from a non-descript ocean, in order to provide a sea level reference for all comparative heights. Along the „shore“, we find several places which lie at or near sea level, such as London and Rome (on the right) as well as the pyramids and the Niagara falls (on the left). Not only are these locations placed randomly along the bottom of the mountain, their properties are also sometimes affected. It is fun to see how the Niagara falls burst out conveniently into the sea and how the pyramids (who everybody knows to be situated in a sea of sand) are having their silhouette reflected in the water.
Much in the same way, the mountain peaks are depicted rather creatively – they look more like a jelly bag cap than a mountain peak. Our virtual mountain is topped by the Dhaulagiri, a peak in Nepal considered at the time to be the highest mountain in the world. Note the lovely narrative details such as the little volcanos, the air balloon to the right or the condor to the left, all instances of compared heights.
This 19th century cartographic specialty – which once has been called „the comparative machine“ – integrates two conventions: the map and the diagram. It never ceases to amaze me that the marriage of two scientific schemes creates a rather unlikely virtual world. I guess that is what people call science fiction – fiction arising from science.
Images via David Rumsey Cartography Associates. I recommend the excellent book “Le monde sur une feuille” (Jean-Christophe Bailly, Jean-Marc Besse, Gilles Palsky, 2014), which focusses only on this particular type of maps and presents many, many beautiful examples. The quote of the “comparative machine” is taken from Jean-Christophe Bailly’s preface (p. 4).