Aperture 7 Gamma

Aperture 7 Gamma is a service aperture of the fourth category, situated on the seventh bench of the eastern stair of Spiral76-Gamma and administered, after considerable dispute, as a dependency of Aperture Gamma. It is a plain aperture: a squared opening of 2.4 by 1.1 metres, framed in grey plinth stone, through which the corridor of Bench Seven communicates with the lower landing of the Gamma relay. It admits light, air, and—under conditions set out below—persons. It is not to be confused with Aperture Gamma-7, which marks the entrance to the Lys-Gamma Spiral and lies some four hundred floors distant, nor with the several apertures bearing the same bench number in the northern and western directions of the same spiral.

Construction and first survey

The aperture was cut in the winter of the year recorded in the survey rolls as 1183-A, during the second widening of the eastern stair. The Office of Bench Survey measured it on three occasions and returned two sets of figures, a discrepancy later attributed to the surveyor Marn Ostelby having counted the sill twice. The sill has since been planed to a depth of nine millimetres, which settled the matter without resolving it.

Its plinth stones are unremarkable except in one respect: a surveying party from Aperture Gamma, passing through in the course of the inquiry into the Gamma apertures, noted that the stones of Aperture 7 Gamma returned no resonant frequency whatever when struck. The party's report, filed as an annex to Witness Ledger 44-Gamma, records the observation without comment. Later readers have commented extensively.

The naming dispute

For sixty-one years the aperture was entered in the spiral registers as Bench Seven, Eastern, without further designation. The designation Aperture 7 Gamma was imposed by Concordance 41, Annex 9, which undertook to bring all apertures of the Gamma relay under a single naming scheme. The Office of Bench Survey objected at once, on the grounds that the scheme numbered apertures from the relay outward while the spiral registers numbered them from the stair inward, so that the aperture formerly known as Bench Seven, Eastern, was in the new scheme the seventh from a different direction altogether.

The objection was heard and dismissed. Concordance 44 later restored the spiral registers to precedence, which would have undone the naming entirely had Concordance 41, Annex 9 not been reaffirmed by Concordance 47, Annex 2 in the same session. The resulting position—that the aperture is officially numbered from the relay and officially listed from the stair—has not been revisited since. Clerks of the eastern bench are instructed to enter both numbers and to strike out whichever is queried.

"An aperture may be numbered from any fixed point, provided the point is fixed. The difficulty at Bench Seven is that the point moves with the clerk."

— Concordance 47, Annex 2, marginalium

Restrictions on passage

Aperture 7 Gamma is not a thoroughfare. Passage through it is permitted only to holders of a Bench Seven transit slip, and only between the hours of the second and ninth bells. Slips are issued by the Keeper of the Eastern Stair and are valid for a single crossing; a slip presented twice is retained by the aperture and destroyed. In practice the restriction is enforced by Ostelby's rule, under which any person found on the far side of the aperture without a slip is returned by the same route and entered in the bench roll as having not crossed. The bench roll consequently records eleven crossings in the year 1191-A and none at all in 1192-A, though the corridor on the far side was swept fourteen times.

The aperture is closed with a shutter of banded oak on the first day of each month for inspection. Inspection consists of opening and closing the shutter.

The hum

Since at least the survey of 1183-A, persons standing at the sill have reported a low tone, below the threshold of ordinary hearing, said to be felt rather than heard. The phenomenon is frequently confused in the secondary literature with the sub-audible hum at Aperture 77-Gamma, which is a different hum, at a different aperture, on a different spiral, and which has been documented far more thoroughly. The Office of Audible Records has twice declined to open a file on Aperture 7 Gamma, noting in its second refusal that the aperture "has not been heard to hum, and has been heard to be hummed at."

Marn Ostelby, whose dispute with the Office over this refusal occupied his final years, maintained that the distinction was clerical rather than acoustic. His petition of 1194-A is preserved in the bench rolls, together with the Office's reply, which is a single line.

Scholarly disagreement

The principal controversy concerns whether Aperture 7 Gamma ought to be counted among the dependencies of Aperture Gamma at all. The Fifth Recension of the Aperture Rolls lists it under Spiral76-Gamma without mention of Gamma; the Seventh Recension lists it under Gamma with no mention of the spiral. The Concordance of Dependencies resolves the question by declaring that an aperture belongs to the body that inspects its shutter. Since the shutter of Aperture 7 Gamma is inspected by the Keeper of the Eastern Stair, who holds no warrant from Aperture Gamma, the Concordance would appear to settle the matter against Gamma—yet the inspection is entered in the Gamma ledger, and the Keeper has never disputed the entry.

The Office of Bench Survey takes the view that the question is unanswerable and has said so in writing four times, in increasingly short memoranda.

Inventory of the sill

The sill was cleared on the ninth of the month in 1196-A and its contents entered as follows.

• One transit slip, expired, bearing the mark of the Keeper of the Eastern Stair.
• One brass tally, unmarked, of a type not issued on the eastern stair.
• Grit, grey, 31 grams, retained for comparison with the grit of the lower landing.
• A pencil.

The grit proved identical to the grit of the lower landing, which the Office of Bench Survey has taken as confirmation of nothing in particular. The pencil was returned to the bench desk.