Sympathetic Floor Resonance (I/S-450.00.σ)

Sympathetic Floor Resonance (catalogue designation I/S-450.00.σ) is the branch of sympathetic resonance concerned with the tuning of floors as whole vibrating bodies, and with their tendency to take on the properties of what is stored upon them. It is distinguished from ordinary sympathetic resonance in that its object is not a room or a corridor but a single numbered floor, considered as a plate of stated mass suspended at a stated height. The field is administered jointly by the Chamber of Cartographic Calibration and the Resonance Technicians' Guild, a division of labour that has been contested in writing since the acceptance of Concordance 88.

Doctrine

The governing statement is given in the second recension of the Principle, §12, which holds that "a floor shall be presumed to agree with its contents until measurement shows otherwise" (The Principle of Sympathetic Resonance, §12). Agreement is measured in sigma units, where one sigma is the divergence at which a floor begins to accept the acoustical habits of its holdings without further prompting. Floors below 0.4σ are called quiet; those between 0.4σ and 2.1σ are attentive; those above 2.1σ are compliant and are catalogued separately under the Compliant Floor Register.

The practical consequence has been known since the fieldwork of Tamsin Orell-Wale, whose survey of the upper decimal ranges ran from 14,900 to 15,340 over two seasons. An attentive floor shelving, say, eleven hundred bound volumes of correspondence will develop a faint paper-rustle where no paper moves. A compliant floor shelving the same volumes will answer questions in the manner of the correspondence. Orell-Wale's notebooks record a single entry against Floor 15,102: "The floor has asked after the addressee. I have given it no addressee" (Orell-Wale, Survey Notebooks IV, 17).

Instrumentation and protocol

Readings are taken with a Sympathetic Resonance Engine mounted on a trestle of Sympathetic Stone and levelled to the plate before any measurement is entered. The engine is left to settle for one hour; a reading taken sooner is not admitted as evidence by the Chamber. Calibration follows the ordinary pattern, using Sympathetic Stone dust in the amounts prescribed by the Engine Annex. The floor itself is excited by tapping in the prescribed pattern — four strikes at the centre of each quarter, no strike within two paces of a shelf upright — and the response is compared against the standing plate profile held for that floor number in the Floor Profile Ledger.

Where the designation carries the sigma suffix, as it does here, the engine must also be run through the Sympathetic Floor Index, which supplies the expected figure for the floor's catalogue class. Discrepancies of more than 0.3σ between the Index and the measured response are entered on the pink sheet and referred upward. Pink sheets are not filed by floor; they are filed by the week in which the discrepancy was found, and are retrievable only by someone who already knows the week.

The 15,102 incident

In the winter of Cycle 109, the surveyor Bered Onn maintained a standing order that no work be done on Floor 15,102 without a second reader present. The order was made under clause 7 of Concordance 88, which permits any surveyor to require corroboration, and it was never rescinded. Onn's reason, entered in the floor's file, was that the floor's response had begun to anticipate the tap: the fourth strike arriving, in the plate trace, some twelve milliseconds before the hammer fell. The Chamber's verification unit examined the trace for thirty-one days and concluded that the engine's timing fork had drifted. Onn accepted the finding and asked that the wording of it be kept short. It is four words long: "Faulty fork. Floor cleared" (Chamber of Cartographic Calibration, Verification 22,411).

Subsequent readings on Floor 15,102 have remained below 0.9σ. Visitors are asked not to tap the floor themselves; the tap pattern has been withheld from the public index since Cycle 111 and may be obtained from the Guild on written application.

Dispute between offices

Concordance 88, clause 3, assigns "all determination of floor compliance" to the Chamber of Cartographic Calibration. Clause 3 of the later Third Concordance assigns the same determination to the Resonance Technicians' Guild, and adds, in a marginal annotation believed to be in the hand of the Third Recensor, that "the Chamber shall not be informed until the season turns." Attempts to reconcile the two have proceeded through the Rule of Sympathetic Repeal, which allows either office to petition for the suspension of a conflicted clause by demonstrating its vibrational signature with a Sympathetic Resonance Engine. The signatures of the two clause 3s have proven indistinguishable in every trial but the fourth, and the fourth trial was not witnessed.

"Both clauses are in force. Both shall be obeyed. Where obedience to one is obedience to neither, the matter is reserved."

— Concordance 88, Annex 4, reservation ii

The Guild and the Chamber have accordingly maintained two parallel compliance registers for eleven cycles. They disagree on approximately nine hundred floors, among them Floor 17,403, which the Chamber records as compliant (2.44σ) and the Guild as attentive (1.87σ). The difference is attributed to the Chamber's practice of measuring the gallery before the lamps are lit, and to the Guild's of measuring it after. Neither office regards the other's figure as fraud; each regards it as a figure taken under conditions not proper to comparison, which is worse.

Associated phenomena and related work

Floors in the compliant range are known to interfere with holdings elsewhere in the same vertical run. The Bibliographic Resonance section maintains an open case, never closed, on four consecutive compliant floors in the 40,000s whose shelf-marks were found to have re-sorted themselves into an argument. Resonant Argonium Lamps are not recommended for use on floors above 1.8σ, as the glass has a tendency to hum in agreement with debated contents and, on two recorded occasions, to answer. The narrowness of an attentive floor's response may be sharpened artificially, a procedure treated at length under Resonance Mapping and prohibited below Floor 9,000 except with the Guild's endorsement and a witness who has not previously visited the floor in question.

The chief difficulty of the field remains the one Orell-Wale named in her closing memorandum and no one has since improved upon: a floor can be measured, or it can be left as shelved, and the second measurement cannot be taken in the presence of the first. "The instrument listens," she wrote, "and thereafter the floor is listening too" (Orell-Wale, Survey Notebooks IV, closing memorandum).