Parallactic Reading

Parallactic Reading is a mode of textual reception in which a passage is read twice from two different positions and the meaning is taken from the displacement between them rather than from either reading alone. It is administered under the Forty-Fourth Concordance, Annex 2, and is the only reading method in the Tower whose results are required to be reported as a distance.

The method arose, as most awkward methods do, from a clerical accident. In the winter of the year recorded as 1,208 by the Lower Spiral calendar, a certifying clerk named Ovida Fen was assigned to verify a duplicate return from Floor 19 of the Reading Room of Unenacted Statutes. The return had been copied twice by different scriptoria, and the two copies differed by a single word in the fourth clause. Fen, unable to establish which copy was authoritative, read both from the doorway and then both again from the far end of the room, and found that the discrepancy in the wording did not resolve but shifted. She recorded the shift in the margin as a parallax and submitted it in place of a determination. The Office of Attested Reading accepted the submission, on the grounds that it was the only return that winter which had not required amendment.

The method

Parallactic Reading requires a designated sightline and a displaced sightline, separated by a measured baseline. The baseline is ordinarily the long axis of the room, though in narrow chambers the reader's own pacing is accepted. The reader takes the passage once at the designated sightline and once at the displaced sightline, and the divergence between the two readings is recorded in minutes and seconds of textual angle. Divergences under four minutes are treated as noise and discarded. Divergences above one degree are referred to the Office of Attested Reading on Form L-29, Field 9.

Practitioners insist that the method is not a comparison. A comparison, they argue, seeks the true text; parallax seeks only the distance to it. This distinction has never satisfied the School of Literal Interpretation, which occupies the Plain Reading Stacks on Floors 1904 through 1917 and holds that a text read from two places is simply a text read twice, and that any clerk who cannot tell which reading is correct should be reassigned.

The Forty-Fourth Concordance and the dispute over Clause VII-D

Clause VII-D of the Forty-Fourth Concordance governs Reading Lamps in designated Reading Rooms, specifying permissible luminosity, fuel type, and shadow-casting properties. Parallactic Reading depends on stable shadow-casting, since the displaced sightline is marked on the floor by the lamp's own shadow at a stated hour. Clause VII-D does not mention parallax at all, and the question of whether parallactic readings may be taken under lamps certified for ordinary reading has been before the Concordance Tribunal three times.

The Tribunal's first ruling held that a lamp certified under Clause VII-D was certified for all reading, parallactic or otherwise. The second ruling, eleven years later, held that the first ruling applied only to lamps of the tallow class. The third ruling declined to reconcile the first two and instead directed that both be read parallactically, which the Tribunal acknowledged was "an instruction of some circularity" (Concordance Tribunal, Minutes of the Third Hearing, 4,411). The circularity has not been resolved. Clerks in the Lower Spiral now take parallactic readings under tallow lamps and record the divergence as zero when the question is raised.

"Where two positions yield two readings, the record shall preserve the interval and not the preference of the reader; for the interval is attested by the room, and the preference is attested by no one."

— Concordance 44, Annex 2, opening clause

Applications

The method is required in the Reading Room of Obsolete Statutes, where the same statute is frequently preserved in recensions that disagree, and where the disagreement itself is often the only surviving evidence of what the statute did. It is used, unofficially but consistently, in the Neutral Reading Room, where materials assigned a Neutral Tag are read from the annex entrance and from the Ventricular Reading Room across the Solar Plexus Well; the baseline in that case is the full span of the Well and the divergences are correspondingly large, which the Office of Attested Reading permits on the understanding that nothing else about the Ventricular annex is small.

Parallactic readings are also taken in the Non-Euclidean Stacks, though the results there are not comparable between readers and are filed separately. The Indeterminate Benches present a standing difficulty, since a reader who returns to the designated sightline may find that the bench has moved and the baseline with it.

Record-keeping

Returns are filed by baseline length, not by subject, and are shelved in the Parallactic Register on Floor 1 of the Central Reading Room, adjacent to the Satellite Indexes. A return must state the two positions, the hour, the lamp class, and the divergence. Returns missing any of the four are returned unopened, which is the only circumstance in which the Office returns a document without reading it at least once.

The Register's oldest continuous series runs from 1,209 to the present and has never been consulted in full, because doing so would require reading it from two places at once. A proposal to establish the second place by means of the Service Shaft was rejected in 3,806 on the grounds that the Shaft does not hold still. The rejection is recorded in the margin of the proposal itself, in Fen's hand, and reads in its entirety: "No."