Arpeggio Incident

The Arpeggio Incident was a structural-musical event occurring in Cycle 5,441 on and within Stairwell 44, in which the stairwell's tuning forks — one hundred and forty-four of them, fixed at irregular intervals along the inner rail — were induced to sound together, producing a complex and continuously shifting arpeggio. The sounding was accompanied by physical rearrangement of the stairwell's features: landings exchanged places, three of the seven alcoves migrated upward through the well, and the forty-fourth riser was recorded in two locations simultaneously for a period given in the inquest record as "not less than nine days and not comfortably more." The event is chiefly remembered not for its effects but for its aftermath, the Inquest of the Shifting Stairwell, convened in Cycle 5,442 to determine what, if anything, the stairwell had become.

Preceding conditions

The tuning forks of Stairwell 44 had not been sounded as a set since the recalibration of Cycle 5,203, and the calibration schedule posted at the foot of the well listed them as "held in reserve, indefinitely" — a notation that the Office of Vertical Standards has never satisfactorily explained and has declined, on four separate occasions, to amend. In the winter of Cycle 5,440 a junior clerk of the standards office, Clerk Undermin, undertook to audit the forks against the reserve register. Her audit found the count correct and every fork in its assigned position; it also found, at the forty-fourth position, a fork not listed on the register, apparently undisturbed and of obvious age.

Undermin filed the discrepancy under the standing instruction for unnamed fixtures, which is to leave them where they are found. The instruction is repeated in Concordance 12, Annex 2, with the addendum: "An unnamed fixture is not thereby unreal; it is merely unaccounted for." The fork in question was never accounted for. The inquest later heard testimony that it was the interval between this fork and its nearest neighbour that determined the first tone of the arpeggio, though testimony on the point was divided and the fork itself could not be located after the event.

The sounding

On the date recorded as 5,441.7, a maintenance party under Foreman Iss Bellamy entered the well to replace the lantern brackets at landings six and seven — a routine task, performed some four hundred times a cycle. Bellamy's own account, entered as Exhibit 14 at the inquest, describes an ordinary morning until the moment the party's tool-cart struck the sixth landing rail. The forks "answered one another," he wrote, "not as struck bells answer, each in its own time, but as a held chord answers itself." The arpeggio that followed was described in the inquest record as "complex, shifting, and not unpleasant," a phrase that has been quoted against the inquest ever since.

The rearrangement proceeded for an unknown interval. All members of the maintenance party were recovered, though two were found on landings they had not previously occupied and one was found in the same landing twice — the inquest treats this as a matter of record rather than of dispute. The cart was recovered at the foot of the well, upright, with its contents inventoried and undisturbed. Curator Arpeggio, then a junior curator of the Grand Carillon, was summoned to record the tones and arrived too late to hear them; the office has never been formally forgiven for this, and Curator Arpeggio has since observed that the episode "made my name considerably faster than my work did."

The inquest and the divergence of opinion

The Inquest of the Shifting Stairwell opened in Cycle 5,442 under the chairmanship of Librarian Ostrey Vann and sat for eleven sessions. Its central question — whether Stairwell 44 remained a stairwell that had been rearranged or had become some second thing, stairwell-shaped — produced the archive's most durable disagreement.

Concordance 44, which governs the identity of structures under alteration, holds at Clause 3 that "a stairwell is its risers," and thus that Stairwell 44 had ceased and been replaced. The inquest adopted this reading in its majority finding.

"The risers are the stairwell. Where the risers are not, the stairwell is not. That the replacement resembles the original is a courtesy, not an argument."

— Concordance 44, Clause 3, as read into the inquest record

Concordance Supplement 44-Δ — inscribed, as it happens, following The Soporific Spore Incident, and bearing no other relation to the matter — states at its head that a structure is its interior, and that fixtures may be moved within a structure without disturbing its identity. The minority opinion, filed by Vann himself, relied on the supplement and concluded that no new stairwell had come into being. Vann's dissent runs to forty pages and is, by the assessment of the Bureau of Recensions, "correct, and unlikely to be adopted."

Effects on the calibration register

The practical consequence of the majority finding was that the calibration register could no longer certify Stairwell 44 as a continuing structure, and the forks were accordingly entered as fixtures without a host. The Office of Vertical Standards objected; the inquest had anticipated the objection and left the forks' status deliberately unstated, a manoeuvre the standards office has described in its annual remonstrance as "legislating by omission." A proposal to transfer the forks to Spiral 44, Aperture Delta was raised and quietly abandoned, the aperture being already encumbered by the classification dispute arising from The Soporific Spore Incident.

Investigators entering the well are now required to carry a sounding-fork of their own and to strike it at each landing. This is a safety measure, not a test; the distinction is insisted upon by the standards office and is generally regarded as a formality.

Legacy

The incident is the earliest entry in the open chronology of indeterminate structures, and the Incident Chronology cites it at opening as precedent for every subsequent case in which a place has been found to be two places. Its influence on the Catalogue Lacuna Incident is indirect but acknowledged: the practice of recording a structure's features before ruling on its nature began with the arpeggio transcription, such as it was. The transcription itself — some forty bars in the hand of a clerk since identified as Undermin — is held with the inquest papers and has been performed twice, both times privately, both times with the doors closed.

No further sounding has been recorded. The unnamed fork has not been found, the register still does not list it, and the office's instruction to leave unnamed fixtures where they are found remains in force.