02-007. English, late 17th century, unsigned. Made of boxwood, 4 3/4" along the straight edge, with engraved scales on one side, including a shadow scale from 0 to 50; the lower edge with a scale of degrees from 0 to 90 degrees is read from a line suspended from the apex with a small brass plumb bob and viewed through the two brass pin hole sights. Above is a calendar scale abbreviated in English of the months - the night sky is represented by the five most used stars (PW = Pegasus Wing; Lh = Lion Heart; Be = Bulls Eye, etc). This attractive small quadrant is in fine overall condition and is complete with its original brass pin hole sights and small brass plumb bob. It is virtually identical to the illustration of a quadrant in Edmund Gunter's "Works" (1653).
This type of quadrant was originally described in Gunter's "De Sectore et Radio" (1623) and this form was extremely popular throughout the 17th century. The quadrant could be used to observe and measure astronomical phenomena, to perform the basic tasks of surveying, and to carry out astronomical calculations. Gunter's book lists some of these uses:
to finde the day of the moneth
to finde the houre of the day.
to finde the beginning of day-breake, and end of twi-light
to finde the houre of the night by the stares
to finde the houre of the rising and setting of the Sun, and thereby the length of the day and night
