Lining figures sit upright on the baseline. Oldstyle figures rise and fall like lowercase letters. Most readers do not name the difference; every reader feels it. A press that picks the wrong register is a press that has stopped listening to its own pages.
Running prose wants the descent.
In a paragraph set at 17pt, lining figures stand up like capitals. The eye reads them as proper nouns. A date set 1947in lining figures interrupts the line the way a surname interrupts a list. The fix is oldstyle — figures that descend below the baseline, that ride alongside the lowercase, that do not announce themselves until they need to.
Edition III’s body text is Instrument Serif at 17.25pt with oldstyle numerals enabled at the font-feature level. The first proof had the figures lining; the page felt rude. We did not write that down. We changed the feature setting, pulled the proof again, and the rudeness was gone. We have not gone back.
Numerals are not the count. Numerals are the cadence of the count.
Tabular columns want the rigour.
Footnotes, page counts, the colophon’s pressed-figure column — all of these get lining figures, tabular spacing, and the small caps that ride alongside. The reason is not aesthetic. It is alignment. A tabular column of oldstyle figures shudders under the eye; the ascenders disagree, the descenders bicker, the totals stop reading as totals. The page begins to argue with itself.
The rule, then: prose gets oldstyle, anything that has to add up gets lining. The colophon is the only page where both appear, and the adjacency is deliberate. The lining column is the receipt. The oldstyle paragraph above it is what the receipt is for.
A note on the small caps that ride alongside.
Small caps in our editions are drawn, not synthesised — Instrument Serif ships its own and we use them. They sit at 72% of the cap height, and they are paired with oldstyle figures in marginalia, with lining figures in the colophon. The register is mixed on purpose. We tell the reader, by the figure, where on the page they are reading. They do not have to know that we are telling them.