Timekeeping is very important on board of sea going ships. Correct time is essential for celestial navigation, to navigation using dead reckoning, to use tide tables and to regulate the watch system.

The nocturnal is an instrument to determine the correct time at nigth using stars of the Great Bear or Little Bear. They fell out of use with the advent of the marine chronometer, but were in use until the 19th century. Nocturnals are reliably accurate to within 15 minutes.

This instrument is made of boxwood with pierced heart-shaped handle and brass mounted polaris sight, at the back inscribed with IC. It is beautifully engraved. At the back a compass rose and table with the bearing of certain stars located in the Little Bear and Great Bear, relative to the Pole star. Conceived by Michel Coignet in 1581, nocturnals are really simple analogue computers and delightfully simple to use. You set the date with one ring, point it at the North Star using the hole in the centre and then swing the pointer to the Great or Little Bear (“both bears” on the handle) to read off the time.

Catalogue: NM.7-18

Date: early 1700

L without arm: 22,5

D: 11.7 cm

Middle point/arm: 20.7 cm

Signed: IC

Origin: probably English

Condition: in good and working condition, wear consistent with age and use