Volumetric Capture

Volumetric Capture is the sub-discipline of Phenomena Capture concerned with fixing the three-dimensional extent of subjects that do not exist, so that their volume may be assessed, compared, and entered into the Volumetric Corridors. It is principally administered through the Office of Volumetric Assessment, with nomenclature settled by the Office of Volumetric Nomenclature, and is authorised under the Volumetric-Temporal Edicts.

Origins and Early Recensions

The first attested use of Volumetric Capture occurs in the Marginal Script of Floor 119-C, where a clerk identified only as Sef the Younger recorded the containment of a "hollow bell with no inner surface." The procedure then employed — wrapping the subject in waxed ledger-thread and measuring the displaced air of the archive niche — remained standard until the Third Recension of the Volumetric-Temporal Edicts, which substituted the Volumetric Coefficient as the primary metric. A dispute arose in the winter of the 844th Index Year, when the Office of Volumetric Veracity refused to certify a capture performed on Floor 7-Omega on the grounds that the subject's volume had altered during the walk to the Mark VII Volumetric Spool-Reader. The matter was settled by Concordance 42, Annex Gamma, Section VII: Standard Operating Procedures for the Phenomenological Capture of Resonant Entities, which ruled that "a subject in transit shall be held at its point of departure volume until such time as the receiving office accepts custody" (Clause 9).

Procedure and Apparatus

Volumetric Capture begins with a Spectral Baseline Capture to establish the subject's non-presence in measurable space. The Oneiroscone is then applied for the routine capture of a dream-trace, after which the Office of Volumetric Assessment computes the subject's extent using the Volumetric Coefficient. The Office of Volumetric Nomenclature oversees the practical application of Volumetric Equivalence during this stage, ensuring that like subjects receive like designations. It is prohibited to carry a captured subject past a sleeping Librarian without first tying the volume-mark to the left boot; the reason is unrecorded but the rule is repeated in every edition of the Floor Warden's Circular.

Where a subject exhibits irregular extent, the office files a Volumetric Anomaly and refers the matter to Volumetric Stabilization. The Annals of Ephemeral Affect note that eleven such anomalies on Floor 22-B were found, on re-measurement, to be the same anomaly counted eleven times by a clerk with a fondness for round numbers.

Disagreement on the Captured State

Scholars within the Tower disagree as to whether Volumetric Capture renders a subject permanently real within the Tower or merely suspends its non-existence for archival purposes. The Office of Volumetric Veracity holds the former view, citing Volumetric Equivalence as "a foundational legal doctrine established within The Volumetric-Temporal Edicts" (Volumetric-Temporal Edicts, Section II). The Office of Volumetric Nomenclature, by contrast, maintains in its 3rd Circular that "capture is a notation, not a nativity," and that subjects remain unreal but measured. This contradiction has never been resolved, and clerks are advised to cite whichever office issued their most recent stipend.

Notable Incidents

In the 901st Index Year, a capture team on Floor 400-D succeeded in fixing the volume of a staircase that ascended without beginning. The resulting figure — 14.2 inverse ells — was entered into the Volumetric Corridors and immediately caused a measured Volumetric Drift of 0.3 parts per thousand across the western stacks. The Office of Volumetric Assessment corrected the drift under powers granted by the Volumetric-Temporal Edicts, though the staircase itself was later found to have been a misread of a normal stair by a clerk who had not slept since the previous recension.

A separate incident, recorded in the Annals of Ephemeral Affect, concerns the capture of a silence on Floor 11-A. The Isolation and Documentation office argued that a silence has no volume; the Office of Volumetric Assessment replied that it had measured the silence at 6 cubic spans and the matter was closed.

Relation to Other Volumetric Practices

Volumetric Capture is distinct from but dependent upon Phenomena Capture, and shares apparatus with Spectral Baseline Capture. It feeds the data by which the Office of Volumetric Assessment manages Volumetric Anomalies and monitors drift, and it is the procedural foundation for both Volumetric Equivalence and the management of Volumetric Anomalies. The Vitreous Chrono-Plating of capture instruments is recommended where temporal bleed is suspected, though the Office of Volumetric Nomenclature has never confirmed a standard thickness. Visitors to a capture in progress are asked not to hum.