Horizontal Pedestal Sundial Signed W.W. Wilson

This round copper horizontal sundial has an hour scale marked from VI to XII to I to VI. The scale is divided to quarter-hours. The gnomon, which is at an angle of about forty degrees, fits in a groove on the plate of the dial (note that the latitude of Pittsburgh is 40.44 degrees). The gnomon and screw that holds it in place are stored separately. On either side of the gnomon on the base of the dial are tables of the equation of time, indicating the time to be added to or subtracted from the time shown on the dial at different days of the year. In front of the gnomon is a circular glass mirror, inset into the plate of the dial. Inscribed around the mirror are eight directions (S, SW, W, NW, N, NE, E, and SE), as well as the phrase: Direction of the Clouds.
Another mark on the object reads: Made and Sold By W.W.Wilson. Pittsburg. A further mark reads: PATENT (/) applied for. A Latin inscription reads: "HORAS NON NUMERO NISI SERENAS." This motto, found on several sundials, has been translated as “I count only the bright hours.”
Wilson applied for a design patent May 9, 1859 and it was granted July 5, 1859. In the design, the hour scale runs from V to XII to VII and is divided to 5 minute intervals. Other inscriptions also differ.
There was a William W. Wilson, watchmaker and jeweler, who was active in Pittsburgh from about 1835 until at least 1854. According to Whisker, Wilson died in 1865.
Accession file.
William W. Wilson, “Design for a Sun Dial,” U.S. Design Patent 1115, applied for May 5, 1859, granted July 5, 1859. This is handwritten application is on the database of the U.S. Patent and Trademark Office under patent number D001115.
James Biser Whisker, Pennsylvania Clockmakers, Watchmakers, and Allied Crafts, Cranbury, NJ: Adams Brown Company, 1990, p. 134.
Currently not on view
Wilson, W.W.
place made
United States: Pennsylvania, Pittsburgh
Physical Description
glass (overall material)
copper (overall material)
overall: 11 cm x 22.5 cm x 22.5 cm; 4 11/32 in x 8 27/32 in x 8 27/32 in
ID Number
accession number
catalog number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History


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