Carte figurative et approximative de la houille anglaise exportee en 1864
The pattern
This still is filed under Data as proof.
Define
A chart, map, or count that is the argument, not an illustration next to the argument.
Mechanism
Sighted evidence. The reader is asked to believe their eyes: a bar, a share, a spread on a map.
Verdict
The claim is comparative or quantitative and the figure can be read without a caption doing the sell.
Why it works
A single hue used for a single quantity means every comparison on the sheet is a width comparison, and the fraying from one trunk into hundreds of filaments does the argument by itself - concentration at source, dispersion at destination. The inset chart is doing separate work: the map answers where it goes, the stacked area answers how much stays home and in what uses, and keeping them as two graphics on one sheet avoids overloading the map. Naming Hunt with page numbers and stating the millimetre-per-tonne rule turns a picture into an auditable document.
Steal this when
Use it when one source dominates a market and you need the audience to feel the asymmetry rather than concede it. The trunk-and-filament shape is the right form for distribution, supply chain or channel-spend pieces where the story is that everything comes from one place and goes to a hundred.