Epact Scientific Instruments of Medieval and Renaissance Europe

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Nocturnal And Quadrant
Signed by Lorenzo della Volpaia
Dated 1511; Florence
Brass; 77 mm in diameter

The nocturnal is composed of a circular disc divided around the circumference with a calendar scale read anti-clockwise to 5 days. Within this is a volvelle disc with a portion of its edge notched with 15 teeth. Concentric with the teeth are four scales. The scale closest to the edge is graduated only for the same distance as the arc of the teeth for hours reading anticlockwise 5 to 12 to 8. Within this is a scale marked 'H' reading from January '7 7 6 6 6 5 5 5 4 4 4 4 4 4 4 5 5 6 6 7 7'. Within this is a further scale marked 'M{inuta?}' reading from January '31 18 57 38 15 53 27 7 46 32 22 20 24 35 54 13 38 0 25 45 9 24 36 19'. Within this is a month scale. A rule mounted at the centre is not original and makes the instrument unusable by blocking the sighting hole.

The second face of the instrument carries at the centre the hour diagram for an Italian hours dial (9 to 23) for latitude 43? flanked on each side by the two halves of a calendar scale. Beneath the diagram is a scale of 90? reading to one degree. To the left of the diagram is the signature written in a scroll, and to the right, also in a scroll, the latitude. Above the hour diagram is a scale of three rings the middle one of which is a scale of months, the outer the symbols of the zodiac signs (two to each month), and the inner a series of twelve numbers '7 8 6 5 5 4 4 4 3 4 5' represented by the letters of the alphabet 'A' to 'H' (1 to 8). At the centre of the diagram is the number 'XIII'.

Provenance: Vincenzo Viviani.

Anthony J. Turner

Istituto e Museo di Storia della Scienza, Firenze
Inventory no. 1305

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