demonstration Quadrant by W&S Jones, London
Quadrant on stand. 21 cm heigh
Type of object:
Astrolabe en Quadrant
Time period:
Britain rules the waves + France
Place:
135 Hoborn London
Date:
1792
Maker / Author:
William and Samuel Jones
Publisher / Printer:
W. S. Jones
Dimensions:
21 cm heigh, diameter baseplate 10 cm, radius quadrant: 10.5 cm
Material:
Brass
Graduation:
0-90°
Inscription:
W & S Jones 135 Holborn London
Provenance:
Crijns & Stender who bought it from the widow of a German collector
References:
Harriet Wynter and Anthony Turner, scientific Instruments, page 10-13
-Gloria Clifton, Directory of Britisch Scientific instrument Makers, page 155
-George Adams, A catalogue of Mathematical and Philosophical Instrument 1795
Description
The quadrant is used to take declination a Zenith distances in degrees with the aid of a quarter circle as proposed by Ptolemy. This type of quadrant is described in: The new Royal Encyclopedia, Vol. 1, Plate 5 (1788). Which is signed by G. Adams.
W&S Jones were registered on the above address between 1792-1800
The brass round baseplate has thee adjustable feet for horizontal adjustment and a 0-360 degrees scale, with 1° subdivisions for measuring the azimuth (horizontal direction) according to the magnetic north pole.
The quadrant has sighting holes at the top to adjust the angle of the rotatable quarter circle to the star or object to be measured. The obtained declination angle can then be read by a plummet line along the engraved 0-90 scale with 1° subdivisions.
The brass weight on this line is from a later date. (Crijns)
Additional information
