The Ξ-4 Anomaly

The Ξ-4 Anomaly is the designation given to a recurring class of positional disturbance first isolated on Floor 9,151 during the winter of the year recorded in the Tower's internal reckoning as 4,882. Unlike the -Ω Anomaly, which alters records after the fact, the Ξ-4 Anomaly alters the relationship between a subject and the surface it occupies: objects, persons, and occasionally whole corridors are found to rest at a slight but measurable angle to every frame of reference available to them. The angle is not visible to the eye. It is confirmed only by instruments, and instruments disagree about it. The Anomaly has been catalogued continuously since its isolation and remains, by the reckoning of the Office of Procedural Integrity, the fourth-most contested entry in the current Quarterly Anomaly Digest.

Discovery on Floor 9,151

The Anomaly was first recorded by Archivist Sennet Vole, whose survey of the floor's eastern stacks produced a reading of 0.4 degrees of inclination in a reference plumb that had been certified level eleven days earlier. Vole's initial Declaration was lodged under a provisional class, Ξ, reserved for disturbances "affecting the ground of measurement rather than the thing measured" (Second Concordance, Annex 9). The suffix 4 was appended after three further readings on the same floor returned values of 0.4, 0.4, and — on a plumb of separate manufacture — 0.41. The rounding convention adopted at the time has never been revised, and the discrepancy of that third reading is the subject of a standing protest filed by the Instrument Makers' Bench of Spiral Nine.

Vole's original plumb is preserved in a case on the floor where it was read. Visitors are asked not to lean on the case, as leaning disturbs the reading, and the reading is the exhibit.

Behaviour and measurement

Subjects within the field of a Ξ-4 event report no sensation of tilt. A clerk standing squarely in a corridor on Floor 9,151 will demonstrate, on measurement, a lean of four-tenths of a degree toward the nearest stairwell. The lean is consistent across all persons and objects in the affected area, which has led to the characterization recorded in the Declaration of Anomaly as "a disturbance of the frame, not of the occupant" (Declaration A-9,151/3). The direction is always toward a stairwell, and always the stairwell down which the subject is least likely, in the ordinary course of duty, to descend. No mechanism for this preference has been proposed that has survived review.

The Anomaly does not displace its subjects. It establishes a fixed inclination which the floor, and everything on it, then maintains. Corridors measured during an active Ξ-4 event remain level to the touch and sloped to the instrument. Water poured on the floor runs, slowly, toward the stairwell. This was demonstrated in 4,889 by the surveyor Maret Quill, whose demonstration flooded the eastern stacks to a depth of two fingers and required the drying of some three hundred volumes. Quill's demonstration is cited in the Anomaly's file; Quill's drying bill is cited in the file concerning Quill.

Classification dispute

The Ξ-4 Anomaly has been classed in three different categories by three different instruments of governance, and no instrument has withdrawn its classification.

The Fourth Concordance, Annex C, classes Ξ-4 among the Procedural Anomalies, on the reasoning that the floor's tilt is a matter of the procedure by which levelness is certified rather than a property of the floor itself. The Declaration of Procedural Anomaly accordingly lists it under Annex C-7 alongside Procedural Chilling, though the two phenomena share nothing but a preference for the margins of a record. The Third Concordance, Annex 2, classes it as a Cartographic Anomaly, since every map of Floor 9,151 drawn since 4,882 has been, by measurement, subtly incorrect. The Office of Procedural Integrity classes it as an ordinary environmental disturbance and has twice declined to open a file.

"The floor is not tilted. The instrument is tilted. The instrument is certified level. Therefore the certification is tilted, and it is the certification we must correct."

— Fifth Concordance, Marginalia on Annex 2

This reasoning has never been operationalized, largely because correcting the certification requires the instrument, and the instrument is tilted. A proposal to correct the certification by certified level instrument was submitted in 4,901 by the Bureau of Adjustments and returned unread, the covering clerk having measured a lean of four-tenths of a degree at his desk.

The Sennet Vole grievance

Vole's standing grievance, lodged 4,894 and still unresolved, concerns the naming of the Anomaly. Vole maintained that the suffix should record the number of independent readings, and that the Anomaly ought therefore to be styled Ξ-4/3. The Office of Nomenclature ruled that slashes were "a concession to haste" (Office of Nomenclature, Ruling 11, fourth recension), and that Vole's third reading fell within the rounding convention already adopted. Vole appealed on the ground that the rounding convention had been adopted after the reading it governed. The appeal was heard and upheld in 4,897, whereupon the Office of Nomenclature observed that the style Ξ-4 appeared in some four hundred and twelve prior citations, and declined to alter it. Vole's grievance remains open. The correspondence generated by the grievance now occupies two shelves on Floor 9,151 and is, by measurement, the most steeply stacked material on the floor.

Current status

The Anomaly remains active and its extent is re-surveyed each quarter. Findings are declared to the Office of Procedural Integrity and published, in redacted form, in the Quarterly Anomaly Digest, where entries concerning the Ξ-4 field are grouped under the digest's standing note on volumetric fields and its advisory that readers should not adjust their own instruments. Whether the field has a boundary — whether a surveyor may walk out of the tilt and into ordinary levelness — was last tested in 4,915 by a party under Surveyor-General Halden Roos, who reported walking for six hours without leaving it. Roos's report notes that the party became convinced they were walking uphill and turned back. The survey was not repeated. Instruments issued for use on the floor are still certified level at issue, and are asked to be returned that way.