Floor 912: The Argent Lantern

Floor 912: The Argent Lantern is a calibration chamber and its principal fixture, located at the nine hundred and twelfth landing of the Tower's central spiral. The floor is not a library in the conventional sense: it holds a single article of equipment, the Argent Lantern, mounted on a plinth of grey basalt at the chamber's centre, and the annular gallery from which that equipment is observed. It is staffed continuously and has been since at least the Ninth Recension, and it appears in no catalogue of holdings except as a cross-reference.

The Argent Lantern itself is a sealed luminary of unknown construction, roughly one and a half metres in height, emitting a steady luminescence that the Guild of Lantern-Lighters has classified — after considerable dispute — as neither flame nor phosphor but a third category, "argent," entered into the registers by that name alone. The floor exists to make use of it.

Calibration functions

Floor 912 serves three distinct calibration regimes, which are run on separate schedules and are not permitted to overlap. The first is the periodic verification of Persistent Glows, which under Eleventh Concordance, Annex 2, must be checked monthly against the Argent Lantern before their certification may be renewed. A Persistent Glow that fails comparison is dimmed to provisional status and its keeper notified in writing; the notice is delivered by hand and signed for.

The second regime is the measurement of wall reflectance in the Argent Vaults, whose deep chambers on Floor 14,142 of the West Wing Annex cannot be assessed by ordinary means. A reflectance standard is struck at Floor 912 and carried down in a sealed case. The third and least frequent is the calibration of luminescence used to identify the spectral signature of the violet ink, a procedure that occupies the chamber for eleven days and during which no other calibration may be undertaken.

The chamber's fitting-out is deliberately plain. Visitors are asked to remove their outer boots at the threshold and to leave them in the alcove provided, as the basalt dust damages the plinth's inscription. The inscription records the floor's commissioning but not the Lantern's origin, which is the subject of the floor's only sustained scholarly quarrel.

The problem of provenance

Fourth Concordance, Clause 19, states plainly that the Argent Lantern was "found in place, and not made," and forbids inquiry into its manufacture. The Seventeenth Concordance, drafted some two centuries later, asserts with equal confidence that the Lantern was fashioned by the Guild of Lantern-Lighters in the year 1140 and installed on Floor 912 two years afterward as part of the settlement that followed the Lantern Crisis of 1142. Neither document has been withdrawn. The Librarians have declined to reconcile them, noting in a marginal annotation on the floor's own register that the two clauses "do not meet."

"Where a fixture is both found and made, the archivist shall record both findings and proceed."

— Fourth Concordance, Annex 7, marginal hand

The practical consequence is that the Lantern's service life cannot be stated. It has been burning, or glowing, without replenishment since the earliest observations on the floor, and the Guild of Lantern-Lighters maintains a standing instruction that no member is to attempt to open it. Two attempts are recorded, in the winters of 1204 and 1388; both were abandoned at the seam, and the second produced a written apology from the Guild that is preserved in the chamber's alcove.

Relations with the Vaults

Floor 912's most consequential relationship is with the Argent Vaults, whose calibration protocols were largely drafted by Librarian-Provisional Argent and depend on standards struck here. The arrangement has not always been harmonious. In the winter of 1391 a dispute arose over whether a reflectance standard struck on a Tuesday could be used on the following Thursday; the Vaults held that it could not, the floor's keeper held that it could, and the matter was referred upward through three offices before being settled by reference to the Fourteenth Concordance, which addresses the question only obliquely and in a passage concerning candles.

The floor also supplies, irregularly, to the Sighing Vaults, though the nature of that supply is not recorded in the open registers. Requests from that quarter are marked with a small crescent in the margin and are honoured without discussion.

Staffing and incident

The floor is kept by a single attendant at any given hour, drawn from the Guild of Lantern-Lighters, who records the Lantern's condition in a ledger at the changing of each watch. Entries are formulaic: the hours, the apparent steadiness of the light, and a single word for the weather in the stairwell. The ledger for the years 1402 to 1419 was lost when it was mistaken for a raw parchment consignment and returned to Floor 112, Annex B; it has not been recovered, and the Guild has since kept a duplicate.

The most fully documented incident on the floor is the Dimming of 1377, in which a junior attendant, Cerwen of the Ninth Watch, recorded a reduction in the Lantern's emission of some four per cent sustained over three watches and reported it upward. The report was received, filed, and answered nine months later with the observation that no reduction had occurred. Cerwen maintained the accuracy of the entry until retirement and was thereafter cited in two separate Concordances as an example of correct procedure and of premature alarm respectively.

Access

Floor 912 is reached by the central spiral and by no other route, and the spiral's numbering places it, by the reckoning of the Sixteenth Concordance, between Floor 441 and Floor 113. It may be visited by appointment, which is granted freely and is rarely sought, since the chamber offers nothing to read and cannot be photographed. The attendant will answer questions about the Lantern so far as the Concordances permit, and no further.