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Astronomical compendium

Astronomical compendium

  • Place of origin:

    London (made)

  • Date:

    1617 (made)

  • Artist/Maker:

    Allen, Elias (designer)
    Allen, Elias (maker)

  • Materials and Techniques:

    Brass, engraved

  • Credit Line:

    Given by the Council of the Royal United Service Institution

  • Museum number:


  • Gallery location:

    British Galleries, Room 56, The Djanogly Gallery, case 6

Object Type
This compass-dial was used to tell the time during the day and also at night. In daytime, the hours are indicated by a sundial. The scale on the quadrant attached to the sundial's gnomon, or pointer, is first set to the correct latitude. The whole dial is then turned until the compass needle points to north on the compass card. In sunlight, the shadow of the gnomon will then indicate the hour on the ring. At night, the pointer on the larger and lower of the two discs is set to the current date engraved on a scale on the back cover. The compass-dial is held up to the eye and the smaller disc rotated until the slot cut in it is aligned with the two 'pointer' stars in the Great Bear. A pointer on this disc will then indicate the hour on the large disc. The age of the moon, measured in days, and the position of the sun and moon in the zodiac are indicated by rotating discs and a pointer on the back of the case.

Historical Associations
This sophisticated astronomical instrument was made for James I (ruled 1603-1625) and is also thought to have been used by his son, later Charles I, when he was Prince of Wales.

The compendium is signed by Elias Allen who was the most distinguished instrument maker of his day. He made the first slide rule and supplied mathematical instruments to the Stuart royal family.

Place of Origin

London (made)


1617 (made)


Allen, Elias (designer)
Allen, Elias (maker)

Materials and Techniques

Brass, engraved


Height: 2.5 cm closed, Diameter: 6.4 cm

Object history note

Designed and made in the London workshop of Elias Allen (born in Ashurst, Kent, about 1588, died in London, 1653); probably made for James I of England. In 1839 it was presented to the United Services Museum by Captain (later Admiral) William Henry Smyth, R.N., FRS., FSA. (1785-1865). At the time of presentation, the compendium was said to have been made for Charles I when Prince of Wales, but the reason for this theory is unrecorded, and the full royal arms engraved on the cover suggest it may instead have been commissioned for his father James.

Bibliographic References (Citation, Note/Abstract, NAL no)

Blair, Claude. 'A Royal Compass-Dial'. In: The Connoisseur, vol. CLVII (December, 1964), pp. 246-48.

Labels and date

British Galleries:
This ingenious instrument tells the time by day using a sun-dial, and at night by sighting on two stars. On the cover are engraved the royal arms and inside are the latitudes of 30 towns in Britain, which helped to set the dial accurately. Elias Allen made scientific instruments for James I and Charles I. [27/03/2003]




Metalwork Collection

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