Star clock — nocturnal and mechanical tide computer, abacus H31

Max. height 12 cm; diameter 9.5 cm, depth 0.7 cm (14 mm), weight 400 g
Reproduction of a star clock (nocturnal) and mechanical tide computer. The instrument dates from 1570 and was built by Humphrey Cole. The original is kept in the British Museum.
Made of zamak and brass, lacquered using a centuries-old technique.
Gift packaging: a beautiful gift box with an insert

Nocturnal — a star clock is a beautiful instrument that allows time to be determined at night by the position of the stars. The device consists of a fixed dial divided into months, with all days of the year marked, a movable dial indicating the hours on a 1–12 scale, topped with an indicator — a moon face — and a long movable indicator arm. In the center of the device there is an aperture through which we sight the Pole Star (North Star) — the fixed point around which other constellations, such as the Big Dipper, revolve. And precisely because the position of the North Star is fixed, we can refer to it the positions of other constellations as they change over time. Our device — a replica of a device from 1570 — is dedicated to the star Kochab in the constellation of the Little Dipper. But most often, and probably most simply, the indicator arm is set to the rear axis of the Big Dipper and the movable dial to the current date. This allows the current sidereal time to be read. The device is universal — it works at all longitudes in the Northern Hemisphere. Please remember that sidereal time does not necessarily coincide with official time. Great fun!

On the other side of the device there is a mechanical tide computer — an abacus, a device that makes it possible to predict the times at which sea tides occur. The instrument consists of a fixed dial marked with degrees from 0 to 360, an hour scale, and a compass rose. Two movable dials are mounted on it. One indicates the lunar month with a 1–30 scale, and the other has an indicator, beneath which there is the shape of the moon, which changes as the indicator is moved.
A wonderful gift for a sailor, fisherman, astronomer, or enthusiast of historic technology.

User instructions in English, French, Italian, and Spanish.

Product of the Spanish company Hemisferium.

The set includes an attractive decorative box with an insert on which the device rests.