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Antique Schrettegger Equitorial Sundial,circa 1820

$2,495.00

Offered for sale is an Antique Johann Schrettegger Equatorial Compass Sundial Augsburg Germany, octagonal brass dial, made by Johann Nepomuk Schrettegger (1764- 1843).

Description: Needle gnomon from center of circle that is calibrated in roman Numerals (III-XII and I-IX) to show hours for the northern hemisphere. The circle hinged to an octagonal base. The Quadrant scale is calibrated in degrees from vertical to horizontal using Arabic numerals. The upper surface is engraved with floral design. The compass is recessed in the base. Underneath is inscribed 'Johann Schrettegger in Augsburg', with the folding hour ring, latitude scale. The maker: Mr. Johann Schrettegger, Augsburg, Swabia, Bavaria, Germany, circa 1820.

Provenance: The Victoria Museum, Melbourne; Skinner's Auction #2652M, May 2013;Bonhams Auction 15778, March 2008; Christie's Auction 34852 Sept. 1992; Dorotheum Nov 2013; Phillips Action #935.

History of Sundials: A sundial is a device that tells time using the position of the Sun, or more precisely using its hour angle, or sometimes its altitude. Known since the most ancient times, it spread from the renaissance to the 19th century and then slowly became obsolete, due to the growing success of horology. People started to be interested again by sundials after the 1980s and this subject is today very popular.

Studying sundials will allow you to discover various disciplines: history, techniques of art (fresco, engraving, etc.), philosophy of mottoes, celestial mechanics, etc.

Understanding sundials: It is possible to design a sundial on any support (plane, cylindrical, spherical...), of any orientation and for any location. This web site shows several types of sundials but other types exist, sometimes more exotic than useful. The layout of a sundial (lines, arcs, texts) can be very diverse and can provide all kinds of information: solar time, civil time, season, date, Sun's declination, hour of sunrise or sunset, hour of another city, ...

If you intend to design your own customized sundial, you will find in this web site everything you need. You can start by downloading the freeware program Shadows that will do all the calculations for you and print all the drawings you need.

Solar time

Solar time is directly derived from the Sun's position, by counting one hour of time every 15° of hour angle as Earth is rotating around its axis in 24 hours, which gives 360°/24 h = 15°/hour.

On a sundial, the noon line corresponds to the moment of culmination of the Sun, when it crosses the local meridian. This line is always contained in the North-South plane and is always vertical on a vertical sundial, regardless of its orientation.

This sort of time depends on the location, i.e. on its longitude.

Longitude correction: All European countries use the same time zone, called CET (Central European Time), except United Kingdom, Ireland and Portugal which use the WET (West European Time) and some countries in the East of Europe which use the EET (Eastern European Time). Countries based on the CET time zone are located between the western part of Spain, with Vigo, and the Polish border in the East, meaning that they represent a range of 2 hours of solar time. For a city located at the east of the CET meridian, hour is shifted towards morning (sunrise and sunset are earlier). For cities located at the west of the CET meridian, hour is shifted towards evening (sunrise and sunset are later).

One shall calculate the longitude correction for its location, by comparing its longitude to the reference meridian (CET meridian is 15° East). Elsewhere on Earth, people shall know where is their reference meridian. The correction, for example, for Besancon, France (6° 02' East) will give: 15° - (6° 02') = 8° 58', meaning (8+58/60)*4 min = 35 min 52 s of time. When the Sun is at the South, in Besancon, it already passed 36 minutes ago at the South of the reference meridian. For a city at the East of this meridian, the correction will be negative (for example, for Warsaw, Poland (21° East), the correction is -24 minutes, so noon at Warsaw means 11 h 36 min at the CET meridian.

Lit: Early Scientific Instruments by R. H. Nuttall, PhD, Pub: Charles Frank Limited, Glasgow; Encyclopedia of Antique Scientific Instruments by John Fitz Maurice Mills, Aurum Press, 1983

Shipping: FREE to the United States. We also will ship worldwide.

Shipping to the Continental United States is FREE. Please look at the picture and read the description, which form a part of the condition description. What you see and what you read is what you are buying

International purchasers should contact sellers at: CAPTAINMADISON@ATT.NET for a shipping and insurance quote to your address and country. International purchasers should appreciate that the Customs Dept. of your country may assess duties, taxes and/or other charges on your purchase as it enters your country, which expenses are not part of the purchase price for this item and remains the sole expense of the purchaser.

This product would make a wonderful addition to any scientific instrument or sundial collection when displayed in a prominent place, being a grand collectible item that would adorn any serious collector's prized scientific instrument and sundial accumulations, while showing a discriminating dedication for fine sundials and other scientific instrument items as well as a devotion to acquiring fine collectibles.

Sellers exclusively use the USPS as its' shipper (insurance available).

Please email sellers to: CAPTAINMADISON@ATT.NET for purchasing, payment, shipping arrangements, requests for more photos, as well as any other inquiries.

Payments may be made by check (must clear), bank checks, postal or bank money orders, Western Union money transfers, pre-payment arrangements, and/or other secure money transfers or payments.

Please regularly visit our other web sites for more sundials and scientific instruments and related products as we shall regularly be adding more products from time to time:

www.antique_scientific_instruments.com

www.oldsundial.com.

www.vintagesundial.com

www.antiquesundials.com


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  • Model: Antique Schrettegger Equi. Dial


This product was added to our catalog on Tuesday 18 February, 2014.

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