Perdurance Cartographers

The Perdurance Cartographers are a recognised body of surveyors concerned not with the location of spaces but with their endurance — the measurement, recording, and where possible certification of how long a place may be expected to remain a place. Where other guilds ask where a floor is, the Perdurance Cartographers ask how long it will go on being there, and refund their fees when the answer proves shorter than the survey.

Origin and the Standing Defect

The body was constituted in the fourth recension year by a schism within the Architectural Cartographers' Guild, whose members had grown impatient with buildings that were drawn accurately and then failed to persist. The break is recorded with unusual bluntness in the schism instrument, now held in the annexe of the Guild of Formal Cartographers:

"A plan of a corridor that is not there on Tuesday is an ornament, not a survey."

— Instrument of Separation, clause 7, cited in Formal Cartography Review vol. 12

The schismatics took the name Perdurance from a term already in use among Metaphorical Cartographers for the quality of a figure that survives its own explanation. The borrowing was contested for eleven years and settled only by Ninth Concordance, which ruled that a guild may take a word from another guild provided it does not take the other guild's members. The Perdurance Cartographers have observed the ruling scrupulously and have not recruited a Metaphorical Cartographer since.

Method

Perdurance is measured in intervals, the unit being the span a surveyed chamber is expected to remain materially unchanged. Intervals are not converted to years; the guild has twice declined to supply a conversion, most recently in a circular of the Vertical Cartographers' Guild that asked, reasonably enough, how long an interval was. The reply stated that an interval is one interval, and that any chamber requiring a shorter answer should be surveyed by someone with a smaller instrument.

Practical survey is conducted by reoccupation. A pair of cartographers occupy the target space, record its dimensions, leave, and return at stated intervals to record them again; the survey concludes when the dimensions agree. Chambers that never agree are classified as perdurally unstable and are recommended for either reclassification or regular inspection. The Guild maintains a standing roster of unstable chambers, presently 214 entries long, of which 61 are on floors that no longer exist and are retained as controls.

Surveyors carry a chalk line, a plumb bob, and a folding rule. The chalk line may not be left in place between visits; this rule was added after the affair of the long corridor on the floor indexed under the letter sigma, where a marked line remained undisturbed for nine years and was found at the end of that period to be marking a corridor that had moved.

The Interval Dispute

The guild's central disagreement is with the Skeptical Cartographers’ Guild, which holds that perdurance cannot be surveyed because the act of reoccupation is itself a change to the space being measured. The Skeptical position, set out in their Registry of Omissions under entry 4,088, is that a room visited twice is not the same room and that the Perdurance Cartographers have therefore been measuring only their own footsteps since the fourth recension year.

The Perdurance Cartographers reply that this is a matter of definition rather than fact, and that Eleventh Concordance annex 2 supports them:

"A thing observed at intervals shall be accounted the same thing at each interval, unless the observer's own presence is the stated cause of the difference."

— Eleventh Concordance, Annex 2

The Skeptics accept the annexe and deny that it applies, on the ground that the observer's presence is very often the stated cause. The dispute has not advanced since; both guilds continue to exchange citations twice yearly, and the correspondence fills four shelves in the reading room on the floor marked with a single aperture.

Notable Surveys

The guild's most cited work is the Survey of the Returning Stairwell, conducted over thirty years by the clerk-surveyor Halvean Orst, who recorded the same stairwell twice weekly and found that it altered on average once every fourteen months, always by the removal of one step and the addition of another elsewhere. Orst's ledger, still the guild's property, declines to say whether this constitutes the same stairwell changing or two stairwells succeeding one another, and notes in the margin that the question was referred upward and not returned.

Less celebrated is the survey of the Cartographers' Auxiliary depot on floor 3,112, certified by the guild as perdurally sound for an interval of forty and found to be a different depot before the ink was dry. The guild refunded the fee, struck the certificate from the register, and thereafter required that certification be countersigned by a second surveyor who had not been present at the first. The countersignature requirement is the only amendment to the guild's practice that has never been challenged.

Relations with Other Bodies

The Perdurance Cartographers are not a parent guild and have never chartered another. They have been twice invited to join the Independent Cartographers and have twice declined, citing the odd position that a body declining to be independent is better placed to say what independence is. They exchange instruments cordially with the Acoustical Cartographers' Guild, whose resonance surveys give a useful secondary reading of a chamber's persistence, and they are the only guild permitted to annotate the acoustical charts in the margin rather than on an overlay.

They maintain a small permanent office known as the Registry of Intervals, staffed by two clerks and a doorkeeper. The doorkeeper's post is the older of the three, and no one has been able to establish which floor the office is on, so the Registry is surveyed by the guild's own members each quarter and has never yet been found unstable.