Great Eastern Spiral

The Great Eastern Spiral is one of the four Great Spirals of the Tower, and the only one of the four whose primary assignment is meteorological. It is an accretion of shelving, balustrades, clerical annexes, and service galleries wound about the rotation designated Spiral 7, and it is administratively coterminous with the eastern arm of the Eastern Stair complex. In the inventories of the Spiral Charter of Cycle 9,447 the Great Eastern Spiral is entered third, after the Great Western Spiral and before the Great Northern Spiral, though the Charter's preamble retains an older ordering that places it first and is still cited by the eastern scriptoria.

Structure and Extent

The Spiral is not a single stair. It is a helical stack of twelve stacked mezzanines, each assigned a band of the meteorological archive, rising through a shaft of recordable diameter 340 cubits at the base and 322 at the seventh landing. The great balustrade of the seventh landing carries a wind register — 214 brass vane indicators on a single shaft, graduated in the units of the Office of Weights and Registrations — which supplies the readings on which the entire meteorological archive depends. The vanes are read twice daily. The readings of the lower half are recorded in the Eastern holdings, which are concentrated in the Eastern Stair Spiral 14 complex; the upper half is recorded on the spot.

At the seventh rotation the Spiral passes through the Eastern Stair, Gamma Corridor, an architectural and jurisdictional nexus where the winding of the stair and the numbering of the annexes famously disagree. Visitors are asked to leave the brass vanes alone; the Register has been unable to establish why this must be said as often as it must.

The Rotation of Cycle 412

The seventh rotation of the Great Eastern Spiral — the period on which the whole of the Spiral's administrative history turns — is recorded as Cycle 412, Spiral 7, a major classificatory period during which the eastern shelves were reordered around the meteorological holdings and the annexes were renumbered for the first time in living memory. The renumbering was not completed. Annexes 41 to 44 remain assigned to numbers that no longer exist, and are cited by those numbers in all subsequent instruments. The Panel of Adjudication has held that this is a defect of the record and not of the annexes, and that the annexes should be consulted as though properly numbered.

"Where a holding has been numbered twice, the later number governs; but where the earlier number has never been retired, the earlier number governs also."

— Spiral Charter of Cycle 9,447, Annex 2

The Great Dampness

The Spiral's present meteorological assignment originates in the Primary Phase of The Great Dampness, which was centred on the Great Vertical Spiral and spread eastward through the connecting galleries. The eastern mezzanines were the first to be given over to instruments rather than to volumes, on the reasoning that what the dampness had already injured could not be further injured by being measured. The Clerk of the Eastern Registers, Adelard Senn, kept a private account of the migration of humidity along the eastern shelves, and his folio — now in the keeping of the eastern scriptoria — is the foundation of the Spiral's meteorological record. Senn objected for the remainder of his tenure to the transfer of his folio and the retention of his name, and the objection was filed, and is filed still.

Scholarly Disagreement

The relation between the Great Eastern Spiral and the Eastern Spiral is not settled. The Second Concordance of Boundaries treats the Eastern Spiral as a separate rotation and the Great Eastern Spiral as a general name for the eastern holdings; the Spiral Charter of Cycle 9,447 assigns them to one administration under a single officer, and the Panel of Adjudication issues determinations for the Eastern Spiral while the Great Eastern Spiral is cited in the same instruments as though it were the eastern branch entire. The panel's rulings of Cycle 61 and Cycle 108 proceed on the first reading; the later rulings proceed on the second. Both are in force. The editors of the present holding take no position beyond noting that the Great Eastern Spiral is catalogued here, and the Eastern Spiral is catalogued elsewhere, and the two records have not been reconciled.

The Spiral's own instruments follow the older practice and refer to it throughout as the seventh rotation. The Panel has declined to resolve the question of whether the Spiral is a place or an operation, observing that it has been both since the renumbering.

Records and Holdings

The Spiral's records are held in the following places:

• Wind registers and vane readings, seventh landing and above; lower readings held in the Eastern Stair Spiral 14 complex.
• Adelard Senn's folio on the eastern humidity, eastern scriptoria.
• Annexes 41 to 44, under the numbers retired in Cycle 412.
• Duplicate copies of the Spiral Charter of Cycle 9,447, at the seventh landing and in the following annex.

The Spiral may be consulted on the seventh landing, which is the only landing accessible on foot. The Spiral is not open on the upper mezzanines at the change of the wind.