Object Record
Images
Metadata
Catalog Number |
58.66 |
Object Name |
Sundial |
Title |
Refractive Sundial Known as the "Dial of Ahaz" |
Artist |
Schissler, Christoph |
Place of Origin |
Germany |
Date |
1578 |
Description |
Prior to 1895 the Dial existed as separate pieces in the collection. At that time, they were assembled in an incorrect configuration and have since been disassembled. A reproduction base in the shape of a figure of Hercules was made in 2001, but it is unlikely that such a figure would have been used on this piece. This compass may not be original to the piece, and its face and part of the gnomon are missing. The instrument is marked for equal and planetary hours, common and Italian hours, with appropriate conversion tables. The base is elaborately decorated with a Biblical relief of the two miracles of Isaiah, and the bowl with the Zodiac. This type of dial requires both a vertical gnomon and a diagonal gnomon. In the present example, the former would consist of a pointed rod in the center of the bowl (now occupied by a compass); the latter of a figure holding a staff (part of which is restored), mounted to the rim. A string from the center to the end of the staff would form the second gnomon. Engraved. "CHRISTOPHERUS SCHISSLER GEOMETRICUS AC ASTRONOMICUS ARTIFEX AUGUSTAE VINDELICORUM FACIEBAT ANNO 1578" along outer rim of the underside of the bowl. |
Label |
This ornate sundial may be the APS's most unusual instrument. It is known as the Dial of Ahaz, after the king of Judah who supposedly invented the sundial in the eighth century B.C.E. Its creator, Christoph Schissler of Augsberg, Germany, was one of the most renowned instrument makers of the 16th century, producing a wide variety of astronomical and mathematical devices. Demonstrating Schissler's mastery of ornate metalwork and mathematics, the Dial is embossed with Zodiac signs. The base illustrates the miracle described in the Bible (Isaiah 38:8) in which time was reversed and the shadow on a sundial moved backwards. Filling the sundial's bowl with water refracts light and moves the shadow cast by the gnomon back ten or twenty degrees, or approximately an hour, creating a clever optical illusion. This sundial was supposedly brought to the New World by a group of German Rosicrucians, a secret mystical order, who settled in the Wissahickon woods near Philadelphia in the late seventeenth century. It came to the APS through Benjamin Franklin's friend Christopher Witt, an associate of that community of hermits, around 1765. |
Material |
Brass and alloy |
Dimension Details |
Bowl: 6 (incl. figurine) x 12 (diam.) Disc: 5.75 (diam.) Later figurine: 4.5 x 5 x 1.5 Stand: 5.5 x 5.75 (diam.) Mss.: 4 x 12.5 Gnomon: 1.5 (length) |
Credit line |
American Philosophical Society |
Search Terms |
16th century sixteenth century Founding Father measurement mathematics astronomy timepiece scientific instrument |