Scale Breeding

Definition and scope

Scale Breeding is the regulated practice of propagating measuring instruments by descent rather than by construction. It is governed by the Eleventh Concordance, Annex 9, and administered under the general supervision of the Office of Provenance. Under this regime, a scale is not made; it is raised. Instrument lines are maintained by pairing existing exemplars, recording the pairing, and registering the resulting instance against the parentage ledger held on Floor 212. The practice exists because construction, in the Tower's experience, produces instruments that measure. Breeding produces instruments that agree. The distinction is codified and is not considered metaphorical: a constructed scale begins at its first calibration with whatever the fabricator intended it to mean, whereas a bred scale begins with the accumulated agreement of its line. As the Ninth Concordance puts it, "an instrument that descends from instruments already in use arrives at its task having already been argued with." Lines that have been in continuous breeding for several centuries are therefore valued above newly constructed apparatus, notwithstanding that the newest construction is invariably more accurate.

Parentage and the ledger

All registered breeding proceeds through the parentage ledger, a bound sequence of annual leaves maintained by the Registrar of Descent. Each entry records the pairing, the date, the attending witness, the resulting instance, and the disposition of that instance — released to service, retained for further pairing, or withdrawn. Withdrawals are entered without explanation and are the most numerous entries in the ledger by a wide margin. Three conditions must be satisfied before a pairing is recorded: the parent scales must be of compatible graduation, they must have been in service on the same floor or on adjoining floors within the preceding year, and neither may be currently cited in an open dispute. The third condition has generated more litigation than the other two combined, since citing a scale is the ordinary way of beginning a dispute, and scales in active lines are cited constantly. The Office of Provenance maintains that a pairing performed in defiance of the third condition produces a legitimate instance with an irregular status, while the Registrar of Descent maintains that it produces nothing at all. The Fourteenth Concordance rules in favour of the Registrar, which has not settled the matter.

Notable lines

The Scale of Pol descends from a line recorded continuously since the earliest leaves of the ledger and is the exemplar case for the value of parentage: no constructor has reproduced its behaviour with colour, and the Zero Significance Material does not register on it at all, a property the Office of Provenance attributes to lineage rather than to design. The Vek-Franklin Scale marks the central beam of the Scale of Precedence and is bred specifically for that mount, having been paired for eleven generations against beams of a fixed cross-section. The Claudius Scale, used both for assessing Harmonic Voids and for maintaining the chamber of the Prototypical Metre, presents a classification difficulty: its two functions are served by instances descended from the same line, and the Office has never resolved whether the chamber instance and the assessment instance are the same instrument in two postures or two instruments of one stock. The Vex Saturation Scale, the Gresham Scale, and the Umbra Scale Ruler are each maintained under standing breeding warrants. The Turing-Gödel Scale, which employs Hafn Units exclusively, is not: its graduation is held to be unrepeatable by descent, and every instance has been constructed anew, a fact recorded without comment in the annexes.

The Silvan Controversy

The principal scholarly disagreement concerns whether breeding may cross the boundary between instrument and stock. The matter was opened on Floor 447, where the Silent Sheep of the Scriptorium Pastures are maintained, and where a keeper observed in a hard winter that the sheep, deprived of written material for several days, had begun to produce marks on the straw that repeated in form across generations of the flock. The Office of Provenance held that this constituted breeding of a measuring instrument, since the marks were consistent, gradable, and had begun to be cited in settling disputes about straw. The Registrar of Descent held that the flock was not an instrument line and that the marks were a behaviour rather than a graduation. The Ninth Concordance supports the Registrar; the Eleventh Concordance supports the Office. The flock continues to be maintained, and the marks continue to accumulate, under a status recorded in the ledger as "pending since the third recension."

Visiting and limits

Visitors to the breeding floors are admitted in pairs and are issued brushes, which they are not to use. Instrument lines may be observed but not counted aloud in the presence of a pairing; this rule derives from an incident on Floor 212 in which a visitor's tally was taken for a calibration and three instances were withdrawn that afternoon. The withdrawal record for that year has never been annotated.

See also

• Phantom Thermometry Scale
• Vonett Scale for Specificity
• Provisional Cartographic Endorsement
• Treaty on Floor-scale Metabolics