Permeative Phenomena

Definition and Scope

Permeative Phenomena are phenomena which pass through solid material without displacing, altering, or otherwise registering against it. They are distinguished from phenomena which merely appear on both sides of a barrier (transmissive) and from phenomena which eat through one (corrosive, a term abandoned in the eleventh recension for reasons the Manual of Unresolved Phenomena declines to give). A permeative phenomenon is present on one side of a wall, present on the other, and absent from the wall, and the wall is expected to remain a wall throughout.

The category was first set out at length in Division VI: Unallocated Phenomena, which claimed it provisionally and has never formally released it. The School of Negative Phenomena holds that the category is empty on principle, since a phenomenon that leaves no trace in matter cannot be said to have interacted with it; the Committee for Ephemeral Phenomena holds the opposite position on similarly confident grounds, and the two offices have not spoken since the matter was raised at the Colloquy of the Fourth Landing in the winter of the year recorded as 3,041.

The Three Grades

Under the Manual of Unresolved Phenomena, permeative phenomena are sorted into three grades according to what they pass through and how completely they omit to disturb it. Grade I phenomena permeate single thicknesses of worked stone and are regarded as routine. Grade II phenomena permeate layered stone, which requires the permeation to occur at two or more interfaces without the phenomenon's own signature appearing at either; these are logged but infrequently studied. Grade III phenomena permeate stone, timber, water, and the observer, and are the subject of the standing prohibition in Ordinance 88: Concerning Standing Clear of Grade III — namely that no agent of any department is to remain within the footprint of a Grade III event for longer than the time required to write down the time.

The grading is not without critics. The School of Negative Phenomena has argued across four successive recensions that Grade III is not a grade but a convenience, and that any phenomenon which permeates the observer has already passed beyond classification into the field of Negative Phenomena proper, where the School's own sorting is acknowledged. Division VI has answered, in a memorandum of 3,119, that the School's argument "would consume the whole catalogue by degrees, as the sea consumes a coast it has been asked only to describe" (Memorandum of the Sixth Secretariate, fol. 44r).

The Wall of Record

The standard reference case is the Wall of Record, a limestone partition on Floor 1,188 against which all permeative phenomena submitted for classification are tested. It was erected in 2,974 and has been scanned, weighed, and sounded at intervals of one month without interruption since. Its current mass differs from its recorded original mass by eleven grains, a difference attributed in the official docket to "handling."

The Wall is the source of the Tower's most-quoted observation on the subject, inscribed above its northern face:

"It went through as though the wall had agreed to it."

— Inscription, northern face, Wall of Record

Visiting staff are asked not to lean on the wall.

The Vantree Dispute

The longest-running disagreement in the field concerns whether permeation leaves a residue in the permeated body. Archivist Vantree of the School of Negative Phenomena maintained that it must, on the grounds that a thing which has passed through a body has, in the plain sense, been there. Her opponents — chiefly Inspector Oleander Bel, then of the Department of Acoustic Phenomena — replied that the plain sense was not evidence. The dispute turned on the Wall of Record and the eleven grains.

In 3,150 a joint commission weighed the Wall a further sixty-two times and found the discrepancy to lie wholly in the mounting brackets, which had been replaced in 3,002 by a fitter whose name does not appear in the maintenance ledger. Archivist Vantree accepted the finding and published a correction; Bel did not accept it, and continued to cite the eleven grains in correspondence until her retirement, after which her successor continued to cite them on her behalf. The brackets have not been weighed since.

Permeation and Other Classes

Permeative phenomena are frequently confused with the Doctrine of Persistent Phenomena, which concerns recurrence rather than passage. A phenomenon may be both; the Circulation Phenomena Annex 7.xi records four instances of repeating permeation through the same aperture, of which three were later reassigned to Class Psi Phenomena after the aperture was found to have been moved. The Annex's reviser noted, with some asperity, that "a door in one wall is not the same door in the next" (Circulation Phenomena Annex 7.xi, reviser's note 9).

The relationship to Formal Classification of Acoustic Phenomena is administrative rather than doctrinal. Because a permeative phenomenon can be heard on both sides of a barrier and not within it, acoustic field agents have historically logged it as an ordinary sound and left the study of its passage to Division VI — a practice the Department of Acoustic Phenomena formalized in 2,911 by adding a note to its classification system, and which the Department has since twice attempted to withdraw.

Current Status

Permeative phenomena remain unallocated. Division VI continues to hold them, the Committee for Ephemeral Phenomena continues to claim them, and the School of Negative Phenomena continues to deny that there is anything there to hold. The most recent attempt to settle the question, Concordance 1,640: On the Allocation of Phenomena Which Pass Through, was amended seven times before its first reading and has not been read.

The Wall of Record stands.