Identifying scientific and navigational instruments

Sundial fragments, compasses, weights and measures of knowing.

Instrument finds include pocket sundial parts (folding gnomon dials, with latitude tables engraved inside lids), compass cards and bowls, drawing instruments (dividers, rules with engraved scales), telescope draw-tubes, and standardised measures — nested cup weights, yard and ell markers, hydrometer bobs.

Engraving identifies: scales, degree marks, latitude numbers, and makers' signatures place and date instruments well. Brass survives kindly; look for silvering traces on dials and the quality of divided scales (hand-divided versus machine-divided marks a horizon around 1800).

Record every engraved word and number, photograph scales flat-on, and measure precisely — these objects are about precision, and their identification lives in the details. Maker signatures can often be matched to documented workshops within a decade.

From the guide library inside Collectors Catalogues, a free app for cataloguing antiques and finds with honest, museum-grade records.

More on domestic objects

Identifying mirrors — Polished metal discs.

Identifying oil lamps — Nozzle, filling hole, and mold.

Identifying clay tobacco pipes — Bowl shape and heel marks.

Identifying agricultural tools — Sickles, billhooks, plough irons, and the seasons written in iron.

Identifying fishing gear — Hooks, net weights, and line sinkers from rivers, lakes, and coasts.

Identifying spindle whorls and loom weights — The flywheels and tensioners of home textile production.

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