Sundial
Physical Object
1986.008.0082a
Santa Margarita (1622)
circa 1620
A sundial and compass device from Santa Margarita is an early version of a pocket watch. The compass was inside the cylindrical body of the piece and was visible through a piece of clear glass situated just under the sundial. The magnetic compass sat on a pin, which allowed it to spin and pivot. The device had to be set on a level surface to allow the sundial card to freely turn and find North. The body of the device was then rotated so the zero mark of the hour scale was in line with the compass and also pointing north. The sundial’s gnomon (the shadow caster) was then flipped up, and the sun's shadow would fall on one of the numeral marks inscribed on the bezel to indicate the local time.
The hinged, triangular gnomon was designed to lay flat for compact storage, and the device was covered by a removable lid when not in use. There is a remnant of a loop fixed to the side of the body, which would have allowed the device to be suspended by a chain or cord. An “Ro” monogram is inscribed below the hour scale, most likely the maker’s mark.
There are several reasons as to why this portable sundial would not have been terribly accurate, especially in the Caribbean. For one, the device was made for a particular latitude – in this case the gnomon is a 45-degree angle, meaning that it was designed to be accurate at the 45th parallel north (i.e., southern Europe). Also, the dial also does not account for the declination of the sun (the angle of the sun above the horizon) which varied in slow-moving, 23.5-degree swings throughout the year. Tilting the device appropriately, though, could correct for any latitude and declination errors. Despite the limitations, this portable sundial/compass would have allowed the user to generally track the span of the day. See also 1986.008.0082b, c--g.
The hinged, triangular gnomon was designed to lay flat for compact storage, and the device was covered by a removable lid when not in use. There is a remnant of a loop fixed to the side of the body, which would have allowed the device to be suspended by a chain or cord. An “Ro” monogram is inscribed below the hour scale, most likely the maker’s mark.
There are several reasons as to why this portable sundial would not have been terribly accurate, especially in the Caribbean. For one, the device was made for a particular latitude – in this case the gnomon is a 45-degree angle, meaning that it was designed to be accurate at the 45th parallel north (i.e., southern Europe). Also, the dial also does not account for the declination of the sun (the angle of the sun above the horizon) which varied in slow-moving, 23.5-degree swings throughout the year. Tilting the device appropriately, though, could correct for any latitude and declination errors. Despite the limitations, this portable sundial/compass would have allowed the user to generally track the span of the day. See also 1986.008.0082b, c--g.
29.78 g Weight