Tableaux d'arithmetique lineaire (French edition of the Commercial and Political Atlas) - Tableau des dépenses des Troupes d'Angleterre depuis 1720, jusqu'en 1786. W. Playfair inv [14319.060]
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
Filling to the baseline forces every peak to be read against the flat peacetime years rather than against its neighbours, so each war shows up as an excursion above a known floor. Ticking every second year at full plate width refuses the compression that would smooth the spikes into a trend. Playfair names the line inside the plot instead of in a legend, so nothing outside the frame has to be consulted to read the chart. Putting the unit key outside the frame keeps the plot clean while still making the scale unambiguous, which matters because the companion plates in the run are drawn at different divisions.
Steal this when
Use it when a cost is normally quoted as an annual average and you want to prove the average hides the spikes. Plot every period, fill to the baseline, and let the floor establish what normal looks like.