Object Details
- Dollond, Peter
- Description
- This brass universal equinoctial ring dial consists of a meridian ring, hour ring, rotating crosspiece or bridge, and sliding suspension ring/handle. The base of the suspension ring is marked with a vernier for the meridian ring that reads to 3 minutes of accuracy. The meridian ring is calibrated on one side for northern and southern latitudes from 0 to 90 to 0 x 2 by single degree. The reverse contains an elongated nautical quadrant for solar altitude calibrated 90 to 0 by half-degree and from 0 to 90 by 10 degrees. The hour ring is calibrated from I to XII x 2 by I. The hour ring is also divided by minutes (20, 40, 60) underneath the hour marks and along the inside edge of the hour ring. The bridge contains a pinhole gnomon sliding over a calendar scale calibrated by month (in 3-letter abbreviations) and day. An engraved line on either side of the pinhole enables the user to line up the gnomon with the proper calendar day. The reverse of the bridge contains a declination scale from 20 to 0 to 20 by units of 0.5 and labeled with S.D. (south declination), AE (equinox?) and N.D. (north declination). The reverse of the bridge also contains a zodiacal sign scale divided into 30s. There is a fitted black or blue leather and wood case with green velvet lining for this instrument.
- There were numerous instrument makers named Dollond, but Peter Dollond is known to have sold sundials in the late 1700s.
- Location
- Currently not on view
- late 1700s
- ID Number
- MA.326980
- catalog number
- 326980
- accession number
- 272472
- Object Name
- sundial, equinoctial
- Measurements
- overall: 3 cm x 20 cm x 28 cm; 1 3/16 in x 7 7/8 in x 11 1/32 in
- place made
- United Kingdom: England, London
- See more items in
- Medicine and Science: Mathematics
- Science & Mathematics
- National Museum of American History
- Subject
- Mathematics
- Timekeeping
- Record ID
- nmah_1215143
- GUID (Link to Original Record)
- https://n2t.net/ark:/65665/ng49ca746aa-a128-704b-e053-15f76fa0b4fa
