StairwellĠSigma-44

Stairwell Sigma-44 is a designated secure access corridor on the lower recorded reaches of Line Sigma, administered under Material Filing Sigma-9 and connecting that line to Aperture Sigma-7 and, by a short spur, to Dock Sigma. It is constructed and has twice been renovated in speckled limestone quarried at Quarry Sigma. The stairwell is not part of the Vertical Tram Line system and is reserved for general access, a distinction the Librarians have had occasion to restate.

Designation and history

The stairwell was recorded for one hundred and forty years as Stairwell 44-B. Following the Vellum Descent Sigma-1 incident, in which a survey party descended past the forty-fourth landing and returned with an inventory of eleven items and no party, the landing was re-designated Stairwell Sigma-44 under the renumbering schedule appended to Descent Protocol Sigma-4. The old designation survives in quarry ledgers and in the marginalia of Sigma-Class Logging, where it is the source of most retrieval errors in the lower Line.

The stairwell was rebuilt to meet the rerouted line under the Reroute Authorization for Line Sigma, an instrument whose surveyor, Clerk Amaranth Vey, spent the winter of the ninth quarter of the current reckoning measuring landings that the reroute had already abolished. Her field notebook records the difficulty without complaint: "The landing is present when approached from above and absent when approached from below, which I have entered twice." The notebook was filed and the discrepancy entered as a standing agenda item of the Concordance on Landings.

Construction and the Sigma-Glass association

The first samples of Sigma-Glass were quarried from Stairwell Sigma-44 and carried to Filing Sigma-9 in a sealed courier case that has since been lost. The Sigma-Glass Precursor is excavated from the deep radial fractures that open in the stairwell's lower flights, and the Sigma-Glass Panes installed at the forty-fourth landing are drawn from that same seam. The panes are inspected at each quarter-turn; the inspection is recorded, but the record is not consulted except when a pane is missing, at which point it is consulted first and found to be incomplete.

Stairwell Sigma-44 is fitted with a Sigma Regulator of the second pattern, which stabilises the corridor against the phenomena for which it is chiefly known. The regulator is serviced from the landing side, and the servicing party is required to leave its boots at the top. No exemption has ever been granted.

The incidence of phenomena

The stairwell's instability is of a mild and well-documented kind, distinct from the unreckonable behaviour of the Backwards Stairwell (Stairwell Psi), which lacks a regulator altogether. Reports from Sigma-44 run to repeated landings, echoes arriving ahead of their causes, and a persistent smell of quarried stone on floors where no stone is dressed. The Sigma Array was calibrated against the stairwell in the sixth quarter and found to under-read by roughly one landing per twelve. The calibration was accepted rather than corrected, on the ground that a known error is an asset and an unknown one is not.

"Let the instrument be wrong by a fixed amount and the wrongness may be subtracted. Let it be wrong by an unfixed amount and we are merely guessing with apparatus."

— Sigma Array, Calibration Annex 2

Two parties have attempted to descend Sigma-44 to the next recorded landing without a reroute warrant. Neither returned a conclusion. Their inventories are held at Dock Sigma and are periodically re-counted by clerks who have never seen the stairwell.

Dispute of the ninth quarter

Four medallions were lost at Stairwell Sigma-44 in the ninth quarter of the current reckoning, and their loss has become the most litigated matter in the stairwell's history. The Third Concordance holds that lost fixtures are charged to the office that last signed the landing, which would place the loss with Material Filing Sigma-9. The Eleventh Concordance, amended more recently and read more rarely, holds that a medallion lost in transit belongs to no office and must be entered as common loss. Both instruments cite the Concordance on Landings in support, and the Concordance on Landings supports neither.

The matter was referred to Clerk Vey, who had by then transferred to the inventory desk at Dock Sigma and declined to return. Her memorandum of refusal, filed in the same hand as her field notebook, observes that "the medallions were counted before they were fixed, and could not have been counted after they were lost, and the count is therefore the only record of an object that has never been present." The memorandum is frequently quoted and has never been acted upon.

Access

Transit to Aperture Sigma and to Dock Sigma is by general access, subject to the wear of the limestone and the ordinary prohibitions of the landing. The Aperture Sigma-7 stairwell terminates twelve metres from the entrance to Spire 44, and parties proceeding beyond the stairwell are asked not to proceed in single file, as the corridor narrows by an amount that has not been surveyed and cannot be agreed upon.