Type 1-B (Environmental)

Type 1-B (Environmental) is the classification assigned to a Type 1 holding whose perimeter has been observed to drift without any corresponding movement of the holding itself. The designation is administered under the Environmental Control Ordinances and is distinct from the Type B Pause, with which it is frequently and wrongly conflated in the field. Where a Type B Pause concerns the suspension of an environmental reading, a Type 1-B concerns the relocation of the ground beneath a reading that has not changed.

Definition and measurement

A holding enters Type 1-B when two successive Environmental Survey passes, conducted no fewer than eleven days apart, return perimeter bearings differing by more than one quarter-arch. The threshold is not theoretical: it was fixed at one quarter-arch after the Ninth Recension of the Survey Schedule found that narrower tolerances captured ordinary settling in the older floors and produced, in the words of the Recension's preamble, "a register of drift that was in fact a register of masonry."

Measurement is taken with a Type-3 Entropic Potential Gauge where the holding exceeds two spans, and by paced traverse where it does not. Baseline stability is ordinarily established beforehand with a Type-2 Laminar Flow Gauge; the practice is retained for Type 1-B even though, as the Bureau of Environmental Cohesion has conceded in circular BEC-441, the baseline so established is itself liable to drift.

Provisionality of the perimeter

The central difficulty of the classification is that a Type 1-B perimeter is provisional. It may be entered, surveyed, sealed, and resurveyed in the ordinary way. It may not be built against. Concordance 88 (as amended by Concordance 88-A) provides that any structure raised within one span of a Type 1-B boundary is to be treated as having been raised at the surveyor's own risk, and that no claim for loss arising from subsequent drift shall lie against the Concordance or its officers.

"Where the ground moves and the holding does not, the ground is the holding's, and the surveyor is a guest upon it."

— Concordance 88, Annex 2

This has produced a small but persistent class of abandoned abutments on the middle floors, known locally as orphan walls, which remain standing after the holdings they were built to serve have drifted clear of them. The Department of Environmental Consistency records orphan walls as Environmental Impact rather than Environmental Interference, a distinction the Bureau of Environmental Cohesion has disputed since the circular of 9 Ember, on grounds set out below.

Dispute between the Bureau and the Department

The two offices disagree as to what a Type 1-B drift is. The Department of Environmental Consistency, which holds oversight of Environmental Resonance Testing and records environmental impact, maintains that drift is an impact — a measurable displacement of the survey envelope — and should be logged as such under the contingency procedure whenever it exceeds three spans in a season. The Bureau of Environmental Cohesion maintains instead that drift is a resonance phenomenon and belongs to Environmental Resonance, collated through Environmental Monitoring and reported annually.

The practical consequence is that the same holding may appear in two registers under two procedures with two sets of figures, neither of which is held to contradict the other. The Third Concordance attempted to close the matter by annexing drift to impact and resonance both, a solution later described by the Bureau's own recension as "a ruling that settles the question by declining to have one." No subsequent Concordance has disturbed it.

The Ember incident

In the winter of the fourth Ember, a Type 1-B holding on Floor 2,241 was surveyed against a boundary that had, unknown to the survey party, already shifted some nine spans eastward. The party worked for six days on a perimeter that no longer enclosed anything, and their returns were entered without qualification. The error was discovered by a lamplighter, Oris Vane, who observed that the Attenuated Lumen-Sconce she tended had begun to reorient toward a corridor the survey expressly placed outside the holding.

Vane's report led to the withdrawal of the six-day return and the adoption of the practice now called cross-bearing, in which the survey party confirms its perimeter against at least one fixture of Type II motility before sealing. The Department subsequently declined to commend Vane, on the ground that a lamplighter is not an officer of survey and her observation had been, in the language of the file, "correct but out of order."

Stabilization and sequestration

Where drift is judged inconvenient rather than dangerous, a Type 1-B may be held in place by an Environmental Stasis Field authorized by the Department, though the field secures the holding and not the floor, and the floor has been known to continue moving beneath it. In one recorded instance, entered as Sequestration 1-B/14, the field held for nineteen years while the floor carried it two full turns of the stair, so that the holding was eventually recovered three landings below where it had been fixed.

Holdings whose drift is judged neither inconvenient nor dangerous are left to themselves and entered in the annual register with the note drifting, unremarkable. Of the two hundred and six Type 1-B holdings currently recorded, one hundred and forty-one carry that note. Environmental Stewards of the Annex maintain the register and ask only that surveyors not enter a drifted perimeter twice in a season, as duplicate bearings are held to confuse the tally.

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