Nocturnal by Simon Keill, 1647

Record summary

Held and catalogued by Museo Galileo, Florence (object number Inv. 1294), this is a nocturnal by Simon Keill, dated 1647. The Atlas places it in the Early Modern Horology period (1600 – 1750) of its Instruments collection. Materials and techniques recorded by the source: brass. Recorded dimensions: diameter 99 mm. The record is illustrated with 2 photographs.

Assembled from the source record's structured fields. Dates and attributions are given as the source states them; where a field is missing the Atlas leaves it blank rather than estimating.

Catalogue description

Atlas type guide

Nocturnals

A nocturnal tells the time at night from the rotation of the stars around the celestial pole. The user sights Polaris through the central hole and turns a long pointer to align with the 'guard' stars of the Little Bear or the 'pointers' of the Great Bear. A calendar scale set to the date converts that angle to the hour.

Nocturnals were used from the sixteenth to the eighteenth century by navigators and travellers. Many are made of boxwood or brass, with tactile teeth on the hour disc so that the time can be counted in the dark.

General guidance written by the Atlas editors about this kind of object. It is not a statement about this particular piece; for that, rely on the source record above and on physical examination.