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This page gives informations to the history of astronomy, to related instruments and to other subjects of astronomy. Some instruments from my workshop are described, but some instruments are not for sell.


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Armillary Sphere with gearing.
Brass, with wooden stand, height ca. 30 cm, diam. of the horizon 15.5 cm, weight ca. 850 g.
Price CHF 2400.00 (look to "instruments" for other currency)

The armillary sphere was known in the middle ages until the renaissance time as a demonstration instrument, and some examples from 16th to 18th century are still in existance. My reconstruction follows in a very free way from an instrument, probably made by Eberhard Baldewein (ca. 1570), which also shows a solar and lunar gearing (L. von Mackensen, Die erste Sternwarte Europas… 400 Jahre Jost Bürgi in Kassel. München 1979, S. 92/93).

The now offered armillary sphere shows quick-motion: One turn of the sphere corresponds to seven days (not one day). So, 4 turns are required for a month, and 52 turns for a year. This is helpfull during demonstrations.

The armillary sphere has a wooden stand, which holds the horizon ring with a 360°-divisions. This ring supports the meridian circle (adjustement for geogr. latitude), and this meridian carries the celestial axis with the fixed earth (Terra) in the centre. The armillary sphere gives the ptolemaic view of the world. The movable sphere has colure-circles, an equator ring (with 2 x 12 hours, fixed to the meridian), both tropical and polar circles and the oblique ecliptic circle with a calendar. Along this calendar move the symbols for sun and moon. There are divisions for the period of the moon (29.5 days) as well as half-/full moon.


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Armillary Sphere, view of horizon and ecliptic.


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Armillary Sphere, detail of the gearing.






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Organum Uranicum.
Equatory (Planetenrechner) after Johannes Schöner, about 1520. The Instrument should replace the calculations with the Planetary tables (Alfonsine tables, Pruthenic tables). The results with an equatory are questionable, and the professional astronomer did rather use paper and ink than such an instrument. The back face shows a mechanical "planetary table" with gearings.
Reproduction not for sell.


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Equatory (Planetenrechner) after Johannes Schöner, back face.


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Astrarium after Giovanni de Dondi (14th century).
Reproduction in a smaler scale (30 cm tall) and simplified, without clockwork. The seven faces show epicyclic motions of the seven old planets Moon, Mercury, Venus, Sun, Mars, Jupiter and Saturn. The Moon-face has a handle: One turn = 1 siderial month. This handle turns all planetes on the seven faces of the Astrarium. The retrograde motion of the planets is easily visible.
Reproduction not for sell.


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Dondi, detail.


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"Pocket"-Equatory (ca. 1400 AD).
Diameter 12 cm. Front: gearing with moon, sun and the inner planets Mercury and Venus. Back: Sun, and the outer planets Mars, Jupiter and Saturn. All movements of the planets are uniforme, and the paths of the planets are concentric circles.


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Back of the "Pocket"-Equatory.


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Reichenbach-Equatories
The monks at the monastery of Reichenbach am Regen in southern Germany invented some equatories at the beginning of the 15th century, following Campanus of Novara, but with gearing. The instruments are lost, and the presented equatories are reconstructions. The moon-instrument is rather speculative.
The Reichenbach-Equatory for Mercury and Venus.
Reproductions not for sell.


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The Reichenbach-Equatory for Mars, Jupiter and Saturn.


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The Reichenbach-Equatory for the moon.


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