small astronomical quadrant
Date: 1776
Inventory Number: DW0750
Classification: Astronomical quadrant
Dimensions:58 × 31 × 31 cm (22 13/16 × 12 3/16 × 12 3/16 in.)
DescriptionThis is a small astronomical quadrant mounted on a table stand with cabriole legs and three leveling screws. Above the tapered column of the stand there are parallel plates with 4 leveling screws. The top plate has the azimuth scale. The scale is divided 0°-180°-0° with divisions every 30' and a vernier reading to 30". There is a brass clamping screw and a long steel slow-motion screw. The column above the azimuth scale carries a bracket with swinging plate and locking screw. The plate's edge is steel. The other edge carries the quadrant framework. In one position the quadrant is vertical; in the other, it is horizontal. A screw gets inserted in a detent to hold the quadrant horizontal.
The quadrant caries a sighting horizontal telescope and a movable telescope that travels over the graduated limb. A hanging spirit level is attached. The limb is divided -15°-0°-100° every 20' with a vernier reading to 30". There is a brass clamping screw and a long steel slow-motion screw. The instrument has a reading microscope.
The horizontal telescope is a refractor and has cross hairs. The moveable telescope is also a refractor with cross hairs, but is unusual in having a right angle prism at the end to direct light to the ocular lens on the side of the tube.
Signedon azimuth circle: Baradelle Fils AParis 1776.
ProvenanceAlain Brieux, Paris, 1962; David P. Wheatland, Topsfield, MA, 1962-1993; Nancy Wheatland Biglow, Medina, Washington; 1993-2018; gift to CHSI, 2018.