Archive of Obsolete Ratios

Definition and scope

The Archive of Obsolete Ratios is the standing repository for proportion systems, scaling factors, and fixed numerical relationships formally withdrawn from use by the Librarians of the Tower. It is catalogued as a subsidiary collection of the Archive of Retired Methods, though the two maintain separate seals, separate accession ledgers, and, since the dispute of 3,102 winters, separate stairwells. The Archive occupies Floors 6,201 through 6,209 and holds some 41,800 recorded ratios in various states of retirement.

A ratio qualifies for accession only after its withdrawal has been issued in writing and its replacement entered into the Ordinance of Standard Measures. Ratios retired without a named successor — a category the archive's own registrars call "orphaned proportions" — are shelved in the mezzanine above Floor 6,204 and are not indexed.

Classification

Accessions are arranged by the manner of the ratio's retirement rather than by magnitude or subject. The five principal classes are: ratios superseded by decree, ratios dissolved by measurement error, ratios abandoned after a building incident, ratios whose governing standard simply ceased to be cited, and ratios withdrawn at the request of the guild that had used them. The final class is the smallest and by far the most contested; three of its eleven holdings have been reclassified twice.

Among the best-documented holdings is the former Silent Proportion-adjacent standard known as the Third Width, a dimensional relationship for acoustic apertures that was withdrawn after the Guild of Resonant Masons found it produced lecture halls in which the last row heard nothing at all and the first row heard everything said two floors above. The Third Width is stored with its original brass gauge, which no longer fits any aperture in the building.

Custody and staffing

The Archive is administered by a single Keeper, a post held since the winter of the Long Inventory by the clerk Ordwin Halve; his predecessor, Marta Quenche, resigned over the question of whether ratios retired twice should be accessioned once or twice, and the resulting memorandum — the Quenche Residue, as it is known in-house — remains unpaged in the second drawer of the third cabinet of Floor 6,206.

Access to the stacks is permitted to any reader who presents a written reason. The reason is read, initialled, and filed; the reader is then admitted. No record exists of a reason having been refused, and equally no record exists of a reader having been admitted with the reason still in hand.

"A retired ratio is not a wrong ratio. It is a ratio that has finished working."

— Ordwin Halve, Keepership Notes, Clause 9

Disputed holdings

The Second Concordance and the Seventh Concordance disagree fundamentally on whether ratios governing atrium proportions fall under the Archive's jurisdiction or under the Reading Room of Obsolete Statutes, which holds that any ratio embedded in a withdrawn statute retires with the statute. The Seventh Concordance's provisions on ceiling height ratios have been retired and reinstated four times since the dispute began; each reinstatement has required the Archive to unshelve, re-shelve, and re-unshelve a single index card, which is now laminated.

A second and older disagreement concerns ratios governing Harmonic Suppression Plates. The Vocalic Charter continues to specify the Silent Proportion as operative, while the Archive holds two prior plate ratios that were withdrawn on the grounds that they produced suppression of the wrong frequencies entirely — in one case, the plates dampened the sound of footsteps while leaving conversation perfectly clear, an outcome the quartermasters of the day found intolerable. The Guild of Resonant Masons has never accepted the withdrawal, and its members continue to cite the older figures in lecture-hall construction without recording the citation.

Access and maintenance

Floors 6,201 through 6,209 are maintained on a cycle of eleven days. Readers are asked not to stand in the doorway of Floor 6,203 while the shelves are being re-angled, as the shelf angles themselves were computed with a ratio now held two floors above and cannot be recalculated on site.

The Archive does not lend. Ratios may be copied by hand in the reading bay, provided the copy is stamped RETIRED at the foot of the page before it leaves the floor. Uncertified copies have twice been cited in active ordinances, both times with consequences recorded elsewhere in the Tower and not detailed here.