Click on the image to zoom. Click and drag your mouse over the
image to move it left or right. Use the small navigation window
to select the area you wish to zoom on. Gunter's quadrant design
is drawn on the face in colored inks and on the reverse is the
declination diagram for mean years. "B.W./AD 1770/calculated
[for] the Meridian/o[f] Boston/July [11th?] 1770." On the
reverse "sic transit/Gloria Mundi." Quadrants helped determine
position on the earth's surface and were used in surveying for
property and boundaries and for navigation at sea.