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Inventory no. 51384 - Epact entry

Epact number: 36819

Nocturnal and Sundial

Signed by Ulrich Schniep
Dated 1581; Munich
Gilt brass; 132 mm in diameter

Main text

This instrument is remarkably close to an instrument by Caspar Vopel dated 1557, which is also in the collection of the Museum of the History of Science. There are some differences, but the similarity extends to most of the detail. It has been suggested that the instrument by Schniep is a copy of that by Vopel, but both could, of course, have been copied from some other source.

Source museum: Museum of the History of Science, Oxford
Museum number: Inventory no. 51,384

Detailed text

The nocturnal side has a zodiacal calendar on the base plate: the calendar scale is marked with the names of the months, divided to 10 and subdivided to 1 day, numbered by 10 (adjusted to the days in the month); the zodiac scale has the names and engraved representations of the constellations, and each sign has a scale 0 to 30 degrees, divided to 10, subdivided to 1, numbered by 10. There are two moving volvelle plates. The first has a pointer, marked 'INDEX SOLIS' and with a sun symbol, extending across the zodiacal calendar, and carries scales for the time and the age of the moon. The time scale had hours 1 to 12 twice, divided to 1, subdivided to 15 minutes, numbered by 1 hour, and each hour position has a point for counting in the dark. The lunar scale runs from 0 to 29|1/2|, divided to 1, subdivided to |1/4|, numbered by 1. The inner moving plate has a pointer, marked 'INDEX LVNAE ET ASPECTVVM' and with a moon symbol, and is engraved with a diagram of planetary aspects marked 'planetarum aspectus'. It is pierced to reveal representations of lunar phases on the first moveable plate. A long central index arm extends beyond the limit of the base plate; around the central pivot is engraved, 'Stella polaris incauda ursæ ma'; the tip of the arm is marked, 'INDEX HORAR PLAVSTRVM VRSRA MAIOR', and with a diagram of the constellation; engraved along the length of the arm is, 'Duae parites plaustri postremae A stella polari cynosurae in rectam ductae solis indie ad diem mensis oblatu positio horamostendunt nocturnam'. The index arm is attached by a later screw and square nut, and there is no central aperture for viewing the pole star.

The handle on this side is engraved, 'Horometri tergum in quo uerus solis locus singulis diebus prope uerum col ligere licet cum aspectibus'.

The sundial side has a Regiomontanus-type altitude dial with sight vanes with double pin-holes, and a three-element articulated arm for adjusting the point of suspension of the plumb-line (missing) on the triangular grid of latitude and zodiacal position. The zodiacal symbols are at the top, with each sign divided by three, and the beginning of each sing indicated by broken lines running through the grid; the latitude scale in from 0 to 65, divided to 5, 5 to 65 subdivided to 1, numbered by 5. The grid is marked on one side, 'Zodiaci Latitudinum Scala', and on the other 'Zodiaci latitudinum quae et poli eleuatio siue borei siue noctii'. The hour lines are numbered both [0] to 12, 'Horae ante meridianae', and 12 to 1 and 12, 'Horae pomeridianae'. There is a solar declination scale to the right of the hour lines, marked with zodiac symbols, each sign divided by three, this scale and the mid-day hour line being marked 'Generalis zodiac et meridianus'. The midnight line is marked 'Medium noctis Septentrio'. The instrument is marked 'QVADRATVM HORARVM GENERALE'.

Around the edge of the sundial side are two altitude scales to be used with the sights and the suspension point set to a position marked 'Centrum Quader'. The outer is a scale of degrees radiating from this point, 0 to 90, divided to 5, subdivided to 1, numbered by 5, marked 'Quaderans Astronomicus'. The inner is a geometrical quadrant or shadow-square scale, 0 to 60 to 0, divided to 5, subdivided to 1, numbered by 5, marked, 'Quaderans Geometricus' and 'VMBRA VERSA' and 'VMBRA RECTA'.


The handle on this side is engraved, 'Horometrifaci es ad omnem regionum latitudinem tam Borealem quam Australem', beneath which is 'R[?]VS'.

E. Zinner, Deutsche und Niederländische astronomische Instrumente des 11. bis 18. Jahrhunderts (2nd ed., Munich, 1967, p. 525.

Jim Bennett

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