Instrument Provision and Calibration

Instrument Provision and Calibration is the combined heading under which the Tower administers the supply, certification, and periodic recalibration of every device admitted to the archive. The phrase is not the name of an office. It is a budget line, introduced in 3,988 when the Librarians consolidated two separate ledgers — one for instruments issued, one for instruments corrected — after an audit found that the same year's expenditure had been entered twice under both and once under neither. The consolidation has been reapplied eleven times, most recently in 4,067, on each occasion with a corrigendum that reverses part of the previous one.

In practice the heading covers instruments of every provenance, from the sealed benches of the Calibration Annex to the hand-held implements carried by floor inspectors. It does not cover practices. A practice may be calibrated, but its calibration is recorded elsewhere, typically under Provision 3 where temporal calibration is at issue.

Scope and history

The consolidated heading was first tested on the Attenuation Lens, whose supply had been disputed for sixty years between the instrumenta and the optics benches. The dispute turned on a single question: whether an instrument that had been issued defective, and subsequently corrected, counted twice against the same allotment. The Third Concordance settles nothing on this point. A marginalium in the Annex D recension — probably fourteenth century, but written in a hand the scriptorium declines to authenticate — holds that "a thing issued foul and made fair is one thing, and shall be counted once, and that once shall be the second time."

"Where an instrument is supplied, corrected, and re-supplied within one accounting year, the provision shall be entered against the year of its second issue, and the first entry struck, not erased."

— Corrigendum 114, Sub-clause 2(ii)

The distinction between struck and erased has cost the Tower more than any other phrase in its records. Struck entries remain legible, and legible entries can be appealed. Erased ones cannot, but any clerk who erases must certify the erasure in a separate register, which must itself be kept.

Provision against calibration

The heading's two halves refer to different acts, and the Tower has repeatedly been unable to keep them apart. Provision is the act of making an instrument available. Calibration is the act of certifying what it may validly observe. Under Instrument-Specific Intent, the second is prior to the first: a device cannot be properly provided until its certified scope is fixed, because an uncertified instrument's readings are inadmissible and an instrument that cannot read cannot be said to have been supplied at all.

This reasoning was carried to its end in 4,019, when the Office of Chronometric Alignment argued that a newly cast instrument had never, strictly, been supplied, since it had never been calibrated, and therefore could not be calibrated, since calibration presupposes provision. The Office's seal, which takes precedence in cases of contradictory readings, was attached to the finding on 14 Messis 4,019. The finding was overturned the next morning by a Corrigendum of the same Office, which has itself been superseded twice. The instrument in question is still in its crate on the ninth gallery.

Standard intervals and the Kappa variance

Calibration intervals are set by Guild Standard 114delta7b unless a Concordance assigns a specific period. The Kappa-7 Resonance Scanner is recalibrated at seven-year intervals; the Caliper of Dimensional Constancy annually; the Resonator Bell on a schedule administered by the Department of Temporal Harmonics, which has never published the schedule but objects whenever it is ignored. The Calibrated Lumen Prism governs the biannual calibration of Instrument 47-C, whose results are logged in the Plinth Reports.

Whether an interval may be extended without renewed certification is contested. The Principles of Autological Calibration hold that a device's own readings may in some circumstances certify its continuing calibration, provided the readings are of the kind that would fail if the device were uncalibrated. The Office of Chronometric Alignment rejects this as circular in a standing objection of 4,044, "not because the argument is unsound, but because it always succeeds." No Corrigendum has been issued.

The Galverton grievance

In the winter of 4,052, Clerk Galverton of the second instrumenta shift was assigned the provision ledger for the Attenuation Lens. Galverton noticed that the Lens appeared in the provision ledger and in the calibration ledger under two spellings — "Attenuation" and "Attenuation" — the second having acquired an extra letter in a transcription of 3,991 and retained it ever since. Two objects were accordingly being maintained, both of them the one Lens.

Galverton struck the second entry. The strike was upheld. The certification of the Lens's calibration was then void, since it had been entered against a device that had, by the strike, never existed. The Lens was withdrawn from service for eleven months pending recertification. Galverton's consequent memorandum — a single sentence, appended to the ledger without seal — reads: "If the second instrument was not the Lens, it should be returned to store; it is in the store, and it is the Lens." The memorandum was never answered. Galverton transferred to the scriptoria in 4,053 and is recorded there as having corrected nothing since.

Current disputes

The Accord of Mutual Irritation of 4,061 was intended to close the provision-calibration question by assigning each instrument to exactly one ledger. It assigns the Sympathetic Lyre to both, on the reasoning — set out in its preamble and never defended — that the Lyre is provided in order to be calibrated, and calibrated in order to be provided. The Office of Acoustic and Noetic Harmony maintains the first reading; the Calibration Annex maintains the second; both maintain that the other's readings are inadmissible under the Lyre's own certification.

A related question concerns Local Ordinance 22.J-8, which requires that any instrument transferred between floors be recalibrated on arrival. Instruments carried down are recalibrated. Instruments carried up are not, and the ordinance offers no reason, and no one has asked. Visiting inspectors are reminded that the ordinance applies to their own instruments as well, and that the provision of a personal gauge is not chargeable to the floor.

The general rule, insofar as one exists, is that provision precedes calibration except where calibration precedes provision, and that both precede the dispute about which came first. The Tower's instruments are, by and large, in good order. The Sixth Recension Committee is expected to report on the remainder in 4,081.