Sorting from largest to smallest is an easy way to arrange objects; a gradient sort is efficient and boring. More interesting is a pyramid sort; for a mountains comparative view, the shape of the sorted objects mimics the shape of the objects themselves. The shortcoming of the pyramid sort (and of the gradient sort) is in the amount of space it occupies. Overlaying smaller mountains on top of the larger ones in a pyramid fashion yields a tight, sorted set.
Finley, in 1827, published the first mountains comparative with an overlaid pyramid sort. Some ten years later, Tanner merged the mountains and rivers compound comparative style with the Finley’ mountain sort. In his work, the mountains were centered, the eye immediately drawn to the tallest, and the rivers were arranged in an inverted trough sort to compliment the mountains with the longer rivers on the edges. By 1850 at least two other cartographers, Mitchell and Cowperthwaite, published the same plate, a testament to its design elegance.
His work was not without flaws. The design pointed to the tallest peak, Dwahalagiri (Everest was ten years away from being surveyed), with the smaller peaks hidden in plain sight. Moreover, he left the middle of the mountains exhibit wide open, wasting space that could have displayed mountains from intermediate height ranges. His exhibit shows 151 mountains and volcanoes, about 25% fewer than the other mountains and rivers comparative maps of the day.
Taken together, flaws and all, this work is beautiful and elegantly uses space. An innovative arrangement for a comparative view, this chart no doubt influenced other comparative maps for decades to follow.
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© Peter Roehrich, 2016