Key of Absent Resonance

The Key of Absent Resonance is the common designation for an access instrument held in the personal keeping of Historiographer Lys and entered in the Register of Unnumbered Instruments under the class keys, resonant, non-material. The Key does not admit to any door. It admits to a frequency. Catalogued formally in Catalog Year 23,447 and in restricted circulation since Amendment 14-f, it is the only instrument in the Tower whose turning is audible solely in rooms that are empty at the moment of turning.

Description and construction

The Key of Absent Resonance consists of a shank, a bow, and a bit, though no examination has ever established of what. The Survey of Instrumental Weights records its mass as "nil, and slightly over." When struck, it produces a tone between 43 and 47 hertz, falling within the band the Protocol for the Measurement of Absent Rooms later fixed as 'structured silence' and thus the same band in which the Choir of Absent Voices is denominated. Whether the Key sounds that band or merely awakens it is a question the Office of Instrumental Audit has formally declined to answer twice.

The bit carries twenty-seven wards, one per Tonal Sigil of the Key of Absent Resonance. Lys's holdings include the only known complete set. Twelve of the Sigils were recovered from the Ventilation Amp Shafts at junctions where Resonance Comparator Arrays had been installed; the remaining fifteen were assembled over eleven years from donations, seizures, and one probate. The set is regarded as complete by the Concordance of Complete Sets but not by the Fourth Concordance, which holds that a set is complete only when the final Sigil has been independently authenticated at the moment of use — an impossibility, since authentication requires the Key.

The requirement of twenty-seven

The Key cannot be turned with fewer than twenty-seven Sigils in place. Attempts to do so are recorded in the Ledger of Premature Turnings, the largest single entry of which belongs to Clerk Ondrej Vasp, who in the winter of A.Y. 23,438 attempted a turning with twenty-six and reported afterwards that the twenty-seventh had been "removed by weather." Vasp's grievance against the Bureau of Sequence Integrity — which he maintained had miscatalogued the Sigil as a Sigil of the Key of the First Step — is preserved in seven volumes, none of them indexed. He was reassigned to the Reading Rooms of Insufficient Depth and continued to submit his grievance annually until his death, after which the submissions continued under his seal for a further nine years.

"Where a set is held to be complete in one office and incomplete in another, the Key shall be deemed turned in neither."

— Fourth Concordance, Annex 9 (c)

Function and the regulation of spillage

Turning the Key is a resonant act, and resonant acts are governed. Aperture Regulation 7 requires that spillage be isolated at key nodal points before any turning exceeding 40 hertz is effected; in practice the operator inserts Resonance Dampeners into the cataloguing stream at three points — the shaft head, the stack junction, and the desk of the attending clerk. The protocol has been invoked four times in the Key's recorded history. On each occasion the Dampeners were inserted correctly and the spillage occurred anyway, a regularity the Resonance Field Analysis of Sub-Level 9 (A.Y. 209) attributes to "the documented independence of the Hum from the instruments installed to contain it."

The Key has twice been used to classify a sustained Absent Sound, most notably in The Case of the Perpetually Absent Goat, where its tone was taken as the reference against which the Goat's bleating was measured and found wanting by a factor of nine. The Perpetually Absent Goat itself was not present for the proceeding and has not commented.

Dispute over custody

The Dispute of the Brass Keys nominally concerns the Thirteenth brass key, but its third recension turns on whether the Key of Absent Resonance should be counted among the Tower's keys at all. The Office of Inventory argues that an instrument admitting to no door is a tone and not a key; the Office of Procedural Emergence counters that the Key emerged within inventory and therefore cannot be inventoried out of it. Both offices cite Amendment 14-f, which each reads as supporting the other. The dispute is now in its fifty-third year and has outlived nine of its original signatories.

For the convenience of visiting Librarians, the Key may not be carried on the eastern stair between the fifth and sixth landings before the lamps are lit. This is not a restriction of access. It is a restriction of resonance.

Current status

The Key of Absent Resonance remains with Historiographer Lys, who has not turned it since A.Y. 23,451, when a turning produced a tone that the Great Re-Cataloguing of the Perpetually Absent Goat was obliged to classify, and could not. The instrument is examined annually by the Office of Instrumental Audit, which reports its weight as "nil, and slightly over" and files the report unaltered each year. The twenty-seven Tonal Sigils are kept in a felt roll on the same shelf as the Key, and the roll is dusted on the first of each month.