Nocturnal And Quadrant
Dated 1543; French
Brass; 71 mm in diameter
The nocturnal side has a zodiac scale with the names of the constellations, each constellation divided to 1/6, subdivided to 1/30, not numbered, and an inner scale is divided 1 to 28. A moveable volvelle disc has an index arm extending across the zodiac scale and carries an hour scale divided 1 to 12 twice, the night hours being indicated also by points, and a scale for the age of the moon, divided 1 to 20. A second moveable disc, marked with the signs of the Ptolemaic planets, has an index arm for the nocturnal function and a circular aperture revealing the phase of the moon.
The quadrant side has a pair of pinhole sights and a plumb-line with a weight (bead missing). Quadrant scale 0 to 90, divided to 5, subdivided to 1, numbered by 10, and a shadow square 0 to 12 to 0, divided to 3 subdivided to 1, numbered by 3, the sides marked 'VMBRE DR[OI]CT' and 'VMBRE VERSE'. The quadrant scale enclosed the unequal-hour lines of the quadrans vetus, numbered 12, 11 / 1, 10 / 2, 9 / 3, 8 / 4, 7 / 5, 6 (noon), and outside the quadrant a zodiac scale with the names of the signs, each divided to 1/6. There is a second set of hour lines for ordinary hours, 4 / 8, 5 / 7, 6 / 6, 7 / 5, 8 / 4, 9 / 3, 10 / 2, 11 / 1, 12 (noon), used in conjunction with a solar declination scale on the right of the hour-lines, marked with signs of the zodiac. There is a second zodiac scale. The sunrise/sunset line is marked, 'LORIZON DE SOLEIL LEVANT'. There are three engraved scrolls; two are blank, one has the date '1543'.
Museum of the History of Science, Oxford
Inventory number 55203
© Museum of the History of Science, Oxford. All rights reserved. Information and images provided here may not be reproduced in any form or by any means without the prior written permission of the museum.
Basic URL: http://www.mhs.ox.ac.uk/epact/catalogue.php?ENumber=11158