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Sundials (2)
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Ever since the Hellenistic period, instruments were built based on the principle of a rod (known as a style) casting a shadow on a quadrant. Such instruments, called sundials, combined two notions: first, the Sun as a time-keeper revolving around the immobile Earth in a uniform daily motion; second, the geometrical analysis of the projection of the style's shadow on surfaces inclined at different angles.

In the simplest sundial model, a vertical style is set in a horizontal quadrant. Three curves indicate the daily paths of the edge of the shadow on specific days of the year. The curve farthest from the style denotes the path at the winter solstice, when the Sun moves at the lowest altitude above the horizon. The intermediate curve shows the path at the spring equinox and fall equinox, when day and night are of equal length. The curve nearest the style marks the path at the summer solstice, when the Sun travels highest above the horizon.

A second series of lines divides the three curves into sections that, while uneven, are covered by the edge of the shadow in one hour each. On the morning of any given day, the shadow appears to tilt westward. For the first six hours of the day, the shadow steadily shortens, reaching its minimum length at midday. It then lengthens in the following six hours until disappearing eastward at sunset.

From a careful observation of the shadow cast on a sundial quadrant, we can therefore determine not only the time of day, but also the time of year.

Objects
Astronomical compendium

Astronomical compendium

Inv. 2478
Maker unknown, German, late 16th cent.

Astronomical compendium

Astronomical compendium

Inv. 2481
Maker unknown, German, ca. 1600

Astronomical ring

Astronomical ring

Inv. 2451
Maker unknown, German?, mid-17th cent.

Astronomical ring

Astronomical ring

Inv. 2452
Maker unknown, mid-17th cent.

Astronomical ring

Astronomical ring

Inv. 2453
Johannes Motter [attr.], Flemish, ca. 1550

Cylinder dial

Cylinder dial

Inv. 2457
Maker unknown, Italian, between 1574 and 1587

Diptych dial

Diptych dial

Inv. 2464
Maker unknown, French or Italian, late 16th cent. - early 17th cent.

Diptych dial

Diptych dial

Inv. 2489
Maker unknown, French, 1573

Diptych dial

Diptych dial

Inv. 3173
Maker unknown, Nuremberg, 1767

Diptych dial

Diptych dial

Inv. 2490
Maker unknown, German, late 17th cent. - early 18th cent.

Diptych dial

Diptych dial

Inv. 2471
Hans Tucher, German, second half 16th cent.

Diptych dial

Diptych dial

Inv. 2469
Maker unknown, German, mid-17th cent.

Equinoctial dial

Equinoctial dial

Inv. 2479
Thomas Haye, Paris, ca. 1705

Horary converter disk

Horary converter disk

Inv. 1287
Maker unknown, Italian, second half 17th cent.

Horary disk for constructing sundials

Horary disk for constructing sundials

Inv. 1304
Maker unknown, Italian, 1672

Horary quadrant

Horary quadrant

Inv. 239
Girolamo della Volpaia, Florence, 1570

Horary quadrant

Horary quadrant

Inv. 155, 156 (cavalletto)
Christoph Schissler, Augsburg, 1599

Horary quadrant

Horary quadrant

Inv. 1306
Joseph Pinam, Italian, 17th cent.

Horary quadrant

Horary quadrant

Inv. 3628
Camillo della Volpaia, Florence, mid-16th cent.

Horary quadrant

Horary quadrant

Inv. 2499
Stefano Buonsignori, Florence, ca. 1580

Horary quadrant

Horary quadrant

Inv. 2520
Giovanni Battista Giusti, Florence, 1568

Horary quadrant

Horary quadrant

Inv. 2524
Giovanni Battista Giusti, Florence, 1565

Horary quadrant

Horary quadrant

Inv. 2525
Giovanni Battista Giusti, Florence, ca. 1575

Horizontal cylinder dial

Horizontal cylinder dial

Inv. 2486
Maker unknown, Italian, 17th cent.

Horizontal dial

Horizontal dial

Inv. 122
Giovan Battista Asini, Italian, 1722

Horizontal dial

Horizontal dial

Inv. 1283
Maker unknown, Italian, late 17th cent.

Horizontal dial

Horizontal dial

Inv. 2484
Georg Zorn, Augsburg, 1613

Horizontal dial

Horizontal dial

Inv. 2475
Nicolas Bion, Paris, ca. 1710

Horizontal dial

Horizontal dial

Inv. 3702
Maker unknown, Italian, first half 17th cent.

Horizontal dial

Horizontal dial

Inv. 2468
Maker unknown, German or Dutch, 17th- early 18th cent.

Horizontal dial

Horizontal dial

Inv. 141
Maker unknown, 17th cent.

Horizontal dial

Horizontal dial

Inv. 134
Maker unknown, French or Italian, 17th cent.

Horizontal dial

Horizontal dial

Inv. 3189
Giovan Battista Magnelli, Florence, 1692

Horizontal dial

Horizontal dial

Inv. 3191
Maker unknown, Italian, ca. 1700

Horizontal dial (incomplete)

Horizontal dial (incomplete)

Inv. 2466
Maker unknown, Dutch?, 18th cent.

Lunar converter

Lunar converter

Inv. 3701
Maker unknown, Italian, 17th cent.

Monumental sundial outside the Museo Galileo

Monumental sundial outside the Museo Galileo

Filippo Camerota, Luise Schnabel, Giorgio Strano

Navicula de Venetiis

Navicula de Venetiis

Inv. 3163
Maker unknown, English, 15th cent.

Nocturnal

Nocturnal

Inv. 1294
Simon Keill, 1647

Nocturnal

Nocturnal

Inv. 2501
Maker unknown, French, 1554

Nocturnal

Nocturnal

Inv. 2502
Pineau [attr.], French, ca. 1600

Nocturnal

Nocturnal

Inv. 2504
Maker unknown, French, 1560

Nocturnal and sundial

Nocturnal and sundial

Inv. 2498
Georg Zorn, Augsburg, 1613

Nocturnal and sundial

Nocturnal and sundial

Inv. 1286
Girolamo della Volpaia [attr.], Florence, 16th cent.

Nocturnal and sundial

Nocturnal and sundial

Inv. 3811
Girolamo della Volpaia, Florence, 1567

Nocturnal and sundial

Nocturnal and sundial

Inv. 2503
Girolamo della Volpaia, Florence, 1568

"Noon cannon"

"Noon cannon"

Inv. 3575
Rousseau, French, early 19th cent.

Polyhedral dial

Polyhedral dial

Inv. 126
David Beringer, G.P. Seyfried, Nuremberg, between 1777 and 1821

Polyhedral dial

Polyhedral dial

Inv. 3193
Girolamo della Volpaia [attr.], Florence, late 16th cent.

Polyhedral dial

Polyhedral dial

Inv. 3261
Maker unknown, Italian, mid-17th cent.

Polyhedral dial

Polyhedral dial

Inv. 2495
Maker unknown, 17th cent.

Polyhedral dial

Polyhedral dial

Inv. 2458
Stefano Buonsignori, Florence, late 16th cent.

Polyhedral dial

Polyhedral dial

Inv. 2459
Stefano Buonsignori [attr.], Florence, late 16th cent.

Polyhedral dial

Polyhedral dial

Inv. 2477
Maker unknown, German, late 16th cent.

Polyhedral dial

Polyhedral dial

Inv. 2460
Girolamo della Volpaia, Florence, 1590

Polyhedral dial

Polyhedral dial

Inv. 2456
Stefano Buonsignori, Florence, 1587

Quadrans vetus

Quadrans vetus

Inv. 662
Maker unknown, German?, late 14th cent. - early 15th cent.

Quadrant

Quadrant

Inv. 2521
Giovanni Battista Giusti [attr.], Italian, 1556

Quadrant

Quadrant

Inv. 3365
Maker unknown, English, 1597

Refraction dial

Refraction dial

Inv. 241
Simone Barocci [attr.], Urbino, second half 16th cent.

Scaphe dial

Scaphe dial

Inv. 2533
Maker unknown, Italian, 17th cent.

Scaphe multiple dial

Scaphe multiple dial

Inv. 2485
Stefano Buonsignori, Florence, 1584

Catoptric sundial

Catoptric sundial

Stefano Barbolini, Gianni Miglietta, 2011

Sundial

Sundial

Inv. 1291, 1302
Maker unknown, German, ca. 1625-1630

Sundial

Sundial

Inv. 2487
Camillo della Volpaia [attr.], Italian, 1542

Sundial

Sundial

Inv. 2488
Camillo della Volpaia, Florence, 1542

Sundial

Sundial

Inv. 246
Carlo Plato [attr.], Rome, 1578

Vertical cylinder dial

Vertical cylinder dial

Inv. 127, 3252
Paolo Contarini, Noto (Sicily), 1844

Vertical dial

Vertical dial

Inv. 2534
Maker unknown, German, ca. 1600