|
| Catalogue |
|
 Quadrant Along the left hand edge is a list of dominical letters for a complete 28-year solar cycle (from the top to the bottom): 'c/d b A g e/f d c b g/A f e d b/c A g f d/e c b A f/g e d e A/b g f e'. The first two entries have been obliterated by a hole drilled in the tip of the quadrant at a later date. The front is marked as an horary quadrant with nine hour curves for equal hours, punched .4./.8. .5./.7. .6./.6. .7./.5. .8./.4. .9./.3. .10/.2. .11./.1:. .12:. The hour curves are intersected by a circular arc representing the equinoxes. The rim is marked as an altitude scale 0? to 90?, numbered by 10? and divided to single degrees. A shadow scale is superimposed on the hour lines, both sides divided into 12 digits, every second digit labelled. There are two sighting vanes mounted on one edge. The pin from which the plumb line is suspended may be a later replacement; the plumb bob itself is missing. The instrument was purchased in 1856 in the Whincopp sale and is described and illustrated in F. A. B. Ward, A Catalogue of European Scientific Instruments in the Department of Medieval and Later Antiquities of the British Museum (London, 1981), p. 56, no. 147; S. Ackermann and J. Cherry, "Richard II, John Holland and Three Medieval Quadrants", Annals of Science (in preparation). Silke Ackermann |