Slit of Ambiguous Time

The Slit of Ambiguous Time is a vertical aperture, 4.2 cubits in height and nowhere wider than a finger's breadth, cut into the western wall of the Standard Time Alcove on Sub-Strata 78γ. It is the only opening in the Tower through which a duration may be admitted without first being measured, and it has been continuously in service since at least the Eleventh Concordance, which refers to it in the passive voice as though it had always been there. The Slit neither emits nor receives light. What passes through it is time, in quantities the Alcove's instruments are forbidden to inspect on arrival.

Construction and dimensions

The Slit is cut through a single block of unstratified grey stone and is chamfered on the Alcove side only, a detail attributed by the Office of Masonic Precedents to a later hand than the wall itself. Two measurements govern its operation. The height, 4.2 cubits, is fixed and may not be altered; the width is described in the maintenance ledger as "nominal" and has never been recorded twice at the same figure. The Warden of Apertures holds that this is a property of the aperture; the Cadastral Surveyors hold that it is a property of the ruler, and the dispute has been standing since the Nineteenth Concordance, Annex 2, was withdrawn and reissued in the same month with the words "of indeterminate width" substituted for a numeral.

Immediately beneath the Slit is a shallow trough of beaten lead, replaced every fourth winter, into which any duration arriving without an accompanying waybill is permitted to pool. The trough is emptied on the last working day of each quarter. Nothing is done with the contents.

Function

Under the procedures set out in the Treatise on Perpendicular Time, a Clerk of the Alcove may present an interval to the Slit for adjudication when its length cannot be settled by ordinary means — most often when a duration is disputed between two floors whose clocks disagree, or when an event is recorded as having occurred both before and after its cause. The interval is passed through the Slit edgewise. What emerges on the western side is returned to the presenting clerk as either antecedent, consequent, or pending, the last being by far the most frequent and the only verdict that requires no countersignature.

The Supervisor of Pendular Time has objected in writing, on nine occasions, that this procedure places an adjudicative function outside the instrument chain that defines Tower Standard Time. The objection is filed each time under the heading "operational" and answered by reference to the Fourth Concordance, which states that "time presented at the Slit is not time kept, but time in passage, and is answerable to no instrument." The Supervisor has asked for a ruling on what "in passage" means. No ruling has been issued. The Vault of Ambiguous Records holds the nine objections in a single folio, bound with the replies, which are identical.

The incident of the Winter Recension

In the winter of the year recorded as 78γ/14, a clerk of the Scriptorium of Corrected Dates named Ilve Marrow presented the same interval at the Slit on eleven consecutive days, in the hope of obtaining a verdict other than pending. On the eleventh presentation the Slit returned the interval marked antecedent and, separately, a second interval of identical length marked consequent, without any record of a second submission. Marrow reported the result and was reassigned. The two intervals were entered in the Alcove register on facing pages, and the register has since been rebound with those pages pasted together, "to prevent comparison," according to the Twenty-Second Concordance, Annex 9, though the Concordance does not say by whom.

"Let no clerk present an interval twice, nor present the same interval under two descriptions, nor inquire what the Slit has done with what it did not return."

— Twenty-Second Concordance, Annex 9, clause 4

Scholarly disagreement

Two readings of the Slit's operation persist. The first, associated with the Bureau of Ambiguous Forms and set out most fully in the marginalia of the Alcove's own copy of the Treatise, holds that the Slit sorts durations by orientation rather than by magnitude, and that pending is not a verdict at all but the condition of an interval that has not yet decided which way to face. On this reading the trough beneath the Slit is not a drain but a waiting room, and its quarterly emptying is a discourtesy.

The second, advanced by the Department of Ambiguous Metrics before its dissolution and never formally withdrawn, holds that the Slit is a measuring instrument of great precision whose scale has simply not been recovered, and that the widths recorded in the maintenance ledger are successive readings of a single graduations system. The Department's Ambiguous Calipers were brought to the Alcove twice in an attempt to establish this. Both visits are recorded. Neither produced a figure. The Protocols for the Calibration of Ambiguous Calipers were amended afterwards to require that any caliper taken within three cubits of the Slit be zeroed first, a rule the Protocol does not explain.

Access and maintenance

The Slit is not to be looked through. Visitors to Sub-Strata 78γ are directed to the eastern face of the Alcove, where the working instruments are displayed, and the western wall is screened by a hanging of undyed wool that is taken down only for the quarterly emptying. The Warden of Apertures signs for the trough, the lead, and the hanging, and for nothing else. Requests to widen the Slit by even a fraction are referred to the Triage Subcommittee for Ambiguous Architectonics, which has not met since the hanging was replaced.