ASTROLABES 13 



59. Astrolabe with Plates for Solar and Lunar Calculations. 1537. 

 Diameter 8| inches. St. John's College. 

 Inscribed + RODES * BRECHTE 1537. Engraved with two 



shields, one bearing a three-flowered 'thistle, the other a Merchant's 

 mark. Grafiti :- ' T N ' and the name ' Pointer ' faintly scratched. 

 Bequeathed in c. 1754 by John Pointer to St. John's College. 



INSTRUMENTS OF THE FOURTEENTH CENTURY 



Illustrations of 



60. Albion. c. 1320. 

 Invented by Richard of Wallingford, of Merton College, Bishop of 



St. Albans. 



61. Rectangulus of Richard of Wallingford. c. 1320. 



Digby 168, f. 61. 



62. Navicula de Venetiis. 



Digby 98, f. 75-7. 



63. Equatorium of Profacius, or Semissis. Temp. Edw. II. 



Ashmolean 1522. 



64. Turket. Temp. Edw. II. 



Ashmolean 1522, f. 177. 



VOLVELLES 



Sun and Moon Volvelles were handy circular scales, by means of 

 which calendrical calculations could be readily performed. The earliest 

 that we have seen dates from before the middle of the i4th cent., and 

 they appear to have remained in use for some time after the advent of 

 printed books. 



A description of their use is found in The Rewle of the Volvelle, MS. 

 Ashm. 191. In a complete instrument there may be as many as seven 

 circles. 



The first and outer circle contains the division of the twenty-four 

 hours and also quarters of hours ; the second contains the twelve 

 months ; the third the twelve signs of the zodiac, with divisions of 

 degrees ; the fourth the times, the rising of the sun and moon ; the fifth 

 the meridian altitude with degrees ; the sixth the age of the moon ; the 

 seventh and last shows the aspects of the sun and moon. 



65. Volvelle or Circular Scales for Lunar and Solar Calculations. 



Quadrant and Zodiac Man. c. 1400-50. 



Diameter 6| inches. Merton College. 



A composite instrument built upon a circular disc with a small 



triperforate bracket for suspension. The circumference is drilled with 



