VM/CON/2026-14 · public technical summary

What the museum actually tested.

The object was not placed in a case without examination. The Verrick record describes visible, ultraviolet, infrared, radiographic, spectroscopic, microscopic, and three-dimensional study. Every method returned usable information. None returned the whole object in all four of its recorded conditions.

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Object under examination

SA.1954.017.a-c

Two curved black limbs joined at a wrapped central grip, a separate cord, and a fitted stone case. The field notebook called the limbs "black glassy stone" by eye. Modern examination treats that phrase as a field description, not a material identification.

01 · Form

Dimensional survey and 3D capture

Established
The relaxed dimensions agree with Cordelia's approximate field measurement. Surface geometry and the present barque-state are recorded to sub-millimetre precision.
Limit
No modern bow-state was attempted. Drawing the limbs would impose an unquantified load upon a laminated archaeological structure.

02 · Surface

Visible, raking, and cross-polarised light

Established
Tooling, wear, coatings, and two old repairs are visible. Worn marks at the terminal fittings cannot be read securely as an inscription.
Limit
The narrow spectral bloom appears only through a small range of crossed-polariser angles. It is repeatable as an imaging response, not visible as a free-standing arc.

03 · Wavelength

Ultraviolet and infrared imaging

Established
UV fluorescence separates later consolidants from the original surface. Reflected IR differentiates the grip wrapping, limb coatings, and repair material.
Limit
No concealed text is recovered. The methods distinguish materials; they do not supply an iconographic reading.

04 · Interior

Digital radiography

Established
The limbs are not homogeneous stone. Overlapping radiographs show a dense outer silicate-rich shell surrounding a laminated internal construction.
Limit
A whole-object CT volume was not acquired: the object's length, metal fittings, and loan restrictions make segmented radiography the lower-risk record.

05 · Material

XRF, Raman, FTIR, and microscopy

Established
The fittings are a gold-silver-copper alloy. The dark surface is silicate-rich; the cord is a bast fibre with a proteinaceous dressing.
Limit
The internal binder and fibre species remain unassigned without sampling. Destructive sampling was not approved for the loan.

06 · Configuration

Historical image comparison

Established
The 1909 trestle series is consistent with three recorded configurations: relaxed, transitional, and drawn. The present object matches the relaxed field geometry.
Limit
Photographs establish former appearance, not the safety of recreating that appearance now.

Findings entered for the record

The tests succeed. Their answers remain partial.

The conservation file does not describe an invisible object or malfunctioning instruments. Its difficulty is representational: surface, structure, material, light, and configuration cannot all be recorded in the same exposure or without changing the conditions of the object.

Finding A

The field description was visually accurate and materially incomplete.

The limbs look like polished black stone. Radiography and surface analysis instead indicate a layered construction beneath a dense, silicate-rich exterior. The record corrects the material assumption without correcting Cordelia's observation.

Finding B

The object was once capable of more than its displayed posture.

Historical photographs and internal construction support the three recorded configurations. Conservation evidence does not justify drawing it again.

Finding C

The spectral response is recorded without being enlarged into a cause.

A narrow band appears in cross-polarised imaging and changes with incidence. The Department reports the response, its repeatability, and its limits. It does not identify it with the 1909 atmospheric arc.

Finding D

No examination supplies meaning.

Technical imaging can identify material, construction, alteration, and risk. It cannot decide whether a barque and bow were intended as the same image, or what a viewer should infer from a red disk placed within the curve.

"The object does not refuse to be recorded. It refuses to be reduced to one record."

Cataloguer's summary, not a finding of the Conservation Department.

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Return from measurement to arrangement.

Working materials

Instrument Room

Align the tracing with the withheld contact print.

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Evidence trail

The Refraction Decision

Follow the measured arc into the Committee's editorial decision.

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Interpretive material

Cataloguer’s Coda

Follow the measured record to the arrangement it cannot settle for you.

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