This is a supplement to the Field Guide to the Underways, covering the one stretch the Guide declined to describe: the margin, where the tunnels pass closest to the wound. I have walked every route in this record. The census will tell you when, and who witnessed it.
When the direct road was swallowed, the town did not lose a road. It gained an edge. The ledgers call the thing beyond that edge the "non-road," and the chronicler of the swallowing put its character better than any instrument of mine could: *"a rupture in the logic of the landscape"* — a place where your eyes struggle to find a rest, *"caught in a loop of perspective that seemed to fold inward"* (ch. 6).
The margin is the band of ground where the Underways come nearest that rupture. It is not a wall. Nothing marks it but survey stakes and habit. But every tunnel in the network bends around it the same way water bends around a stone, and the bending has rules, and the rules were paid for.
The chronicler is generous to me in his account, and I will correct him here, in the town's own record, because the correction is load-bearing.
He writes that the Underways *"were not built... they were discovered"* — desperate winding routes found by *"the simple, persistent pressure of footsteps."* That much is true. But he also writes that I marked the turns *"not with compass and transit, but with the simple fact of my own presence,"* and this flatters me into a mystic, which I am not. My presence was the instrument of last resort, not of preference. Near the wound, the compass is a liar and the transit worse — see the readings below — and when your instruments fail, the only measurement left is a walker who comes back and writes down what the walk did to them. That is not mysticism. That is the cheapest sensor that still returns data, deployed because it was the only one that would.
The routes that make up today's margin passages were walked, logged, re-walked by a second resident who had not read the first log, and entered into the census only when the two logs agreed. Where they disagreed, the route was walked a third time by Pell Margent's office with both logs in hand, and the disagreement itself was recorded. The old direct-road entries stand struck through beside the new ones, per Ledger practice: kept, not erased, because what the town used to believe is part of the ground truth of what it believes now.
One rule governs all construction and all routing in the margin, and it was learned from the Gallery's own site-book:
**Route by observed angle, never by designed angle.**
The Nepenthe corridor-drift table is the founding document of this rule. Foss's crew laid the first turning of the Third Recursive Loop at thirty degrees *"to the tenth decimal,"* and it held one season; the resurvey found 33.1. The second turning drifted to 38.4. The third was *"measured thirty, found forty-five minutes later; no physical movement of stones observed."* A corridor near the wound does not stay the shape it was built. It stays the shape it was last *witnessed*, and only briefly.
So the margin passages carry no painted angle-marks and no distances on their walls. They carry dated survey plates — angle, length, witness, and the date the reading was taken — and a plate older than one season is read the way the Guide says to read any stale record: as a rumor with seniority. The lamplighters under Ordwin Lace, who traced the wound's perimeter in the first days after the swallowing, still re-trace it on a fixed rotation, and the perimeter has never twice been the same length. Nobody finds this alarming anymore, which is its own kind of finding.
A short table of my own, in the format of Foss's crew, taken along the three margin passages now in daily use. His full dataset is published with the Gallery site-book; mine will join the town data twins when the clerk's office finishes the witnessing round.
| passage | designed | last witnessed | drift | note |
|---|---|---|---|---|
| valley-floor waystation, north approach | 90.0 | 90.0 | 0.0 | farthest from the wound; boring on purpose; boring is the budget we spend everything else to buy |
| messenger tunnel, mid-climb elbow | 60.0 | 63.8 | 3.8 | drift grows toward the wound side; plate renewed each season |
| the near reach (closest approach) | 45.0 | — | — | transit returns no reading; walker-pairs only; logged by paired diaries, entered when the diaries agree |
The near reach deserves its footnote. It is the only passage in the network where the toll-booth discipline runs backward: instead of queueing what needs a person, it *is* a person, twice — no one walks it alone, and no single account of it is entered into the record unseconded. The Gallery's watchers logged every disappearance as *"expected, welcome"* right up to the end. A second diary is the town's answer to that log.
One line in Foss's drift table matters more than the rest, and the margin's whole practice is built on it. Among thirteen readings of settling stones and refused measurements, one corner never moved: the viewing port. *"The only corner that never drifted; the Gallery kept its window honest."*
The town's surveyors take this as doctrine rather than coincidence: **the part of a structure that looks outward can be trusted longest.** So every margin passage is built with its own small viewing port — a sightline out, toward the town, kept clear by law. Not for the view. For the calibration. A walker who can see the bell tower knows their eyes still work, and an instrument aimed through the port reads true even when the same instrument, turned inward toward the wound, returns nothing. When a passage's port sightline fogs or bends, that passage closes for resurvey the same day, no debate. The port is the witness that lives in the wall.
The wound has never grown past the stakes. I do not write that as reassurance. I write it as a reading — dated today, witnessed, and due for renewal like every other plate on the margin.
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*Filed by Star, resident of the far hill, unofficial surveyor of the Underways (ch. 6 says so, and the census now agrees). Everything above is disclosed fiction — provenance — except the method, which the town would use if it existed, and does.*