Instruments · Sundial
Sundial by Andreas Vogler, Germany, 1766–1800
- Maker / attribution
- Andreas Vogler (Created)
- Date
- 1766–1800
- Historical period
- Precision & Scientific Horology (1750 – 1850)
- Country of origin
- Germany
- Place
- Augsburg
- Object type
- Sundial
- Materials / technique
- Buntmetall & Glas; gegossen & gesägt & graviert
- Dimensions
- B 5,8 cm
- Holding institution
- Städt. Hellweg-Museum Geseke
- Accession / object no.
- 0000.2357-A
- Credit line
- Städt. Hellweg-Museum Geseke
- Catalogue title (original)
- Äquinoktalsonnenuhr (German)
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Record summary
Held and catalogued by Städt. Hellweg-Museum Geseke (object number 0000.2357-A), this is a sundial by Andreas Vogler, made in Augsburg, Germany, dated 1766–1800. The Atlas places it in the Precision & Scientific Horology period (1750 – 1850) of its Instruments collection. Materials and techniques recorded by the source: Buntmetall & Glas; gegossen & gesägt & graviert. Recorded dimensions: B 5,8 cm. The record is illustrated with 4 photographs.
Assembled from the source record's structured fields. Dates and attributions are given as the source states them; where a field is missing the Atlas leaves it blank rather than estimating.
Catalogue description
Catalogue description from Städt. Hellweg-Museum Geseke (German)
Äquinoktalsonnenuhr nach Augsburger Bauart. Kennzeichnend für die Augsburger Bauart war die achteckige Grundplatte mit dem runden, mit einer Glasscheibe versehenen Kompass darunter. Der Gnomon ("Zeiger") war auf einem Quersteg in dem Stundenring montiert. Im Stundenring waren die Stunden eingraviert. Der Ring konnte mittels eines Scharniers höher oder niedriger ausgeklappt werden, so dass der entsprechende Breitengrad eingestellt werden konnte. Vor bzw. nach der Tages-Nachtgleiche wurde der Zeiger auf die Ober- oder im Winterhalbjahr auf die Unterseite des Ringes gedreht. Dieser Ring wurde so eingestellt, dass er parallel zum Äquator stand. Daher hat dieser Uhrentyp auch den Namen Äquatorialsonnenuhr. Wegen des über das Jahr unterschiedlichen Sonnenstandes, konnte die angezeigte Zeit im Winter bis zu 15 Minuten von der angezeigten abweichen. Neben dem Kompass zur Ausrichtung der Sonnenuhr ist in der Gebrauchsanleitung zur horizontalen Lagerung ein Pendel erwähnt. Die Angaben für sieben Städte finden sich auf der Unterseite. Bei der Sonnenuhr befindet sich eine Gebrauchsanleitung auf Deutsch und Französisch. Sie konnte zusammengeklappt und in dem erhaltenen Döschen verstaut werden. Andreas Vogler übernahm das Geschäft in Augsburg 1766 von seinem verstorbenen Bruder und führte es bis zum Ende des Jahrhunderts. Die Produkte gelten als "Massenware".
Shown in the original language of the source catalogue. An editor-reviewed English translation has not yet been published; we do not publish machine translations as authoritative text.
Historical context
Precision & Scientific Horology (1750 – 1850)
Harrison solves longitude; Mudge invents the lever; Breguet's Paris workshop defines the modern watch.
The longitude problem was solved by the marine chronometer and lunar distance methods; dividing engines made precision scales possible, and observatories set time by transit instruments.
Read the period in the timelineMore instruments from this periodEarlier: Early Modern Horology
Atlas type guide
Sundials and solar time-finders
A sundial tells time from the position of a shadow cast by a gnomon or style. Because the sun's apparent motion depends on latitude, every fixed dial is laid out for a particular latitude, and portable dials either carry a latitude scale or are made for one region. Sundials show local apparent solar time, which drifts against mean (clock) time by up to about sixteen minutes over the year — the equation of time.
Portable dials were the pocket instruments of the sixteenth to eighteenth centuries. Nuremberg and Augsburg workshops produced folding ivory diptych dials with inset compasses; English and French makers sold brass horizontal dials, ring dials and the Butterfield type; Japanese and Chinese makers had their own traditions of compass dials. After mechanical watches became reliable, dials remained in use for setting them, and nineteenth-century heliochronometers were built to correct directly for the equation of time.
What to look for
- The latitude engraved on the dial plate or a latitude arc on the gnomon — it shows where the dial was meant to be used.
- The type of hour lines: equal (equinoctial) hours, Italian or Babylonian hours counted from sunset or sunrise, or unequal temporal hours on early and Islamic instruments.
- An inset magnetic compass and whether a magnetic-declination mark is drawn on its card — a useful dating clue because declination changes over time.
- Maker's signatures and town marks: Nuremberg compass-makers (Kompassmacher) often struck a personal mark and the town's punch.
- Additional scales such as lunar volvelles, wind roses, perpetual calendars or lists of cities with their latitudes.
Dating clues
- Ivory diptych dials are characteristic of Nuremberg between about 1500 and 1700.
- Butterfield-type dials with a bird-shaped adjustable gnomon point to Paris workshops from the late seventeenth century onward.
- Equation-of-time tables engraved on the plate became common after the mid-seventeenth century, once pendulum clocks made the difference between solar and mean time obvious.
General guidance written by the Atlas editors about this kind of object. It is not a statement about this particular piece; for that, rely on the source record above and on physical examination.
Read next:The history timeline
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