14 ASTRONOMICAL INSTRUMENTS 



seventy-two perforations, perhaps for reading or setting the pointers in 

 the dusk. The circles are now held together by a copper rivet, which 

 may have replaced a tubular pin. If so the instrument would have 

 been a nocturnal, or instrtimentum siderale. 1 The incised lines and 

 figures upon the instrument are of two periods : the older being filled 

 with red colour, the later additions with black. Graffito, C. 



66-8. Volvelles. 



MS. Ashmolean, 1522, f. 87, before 1350. 



MS. Ashmolean, 210, c. 1386. 



MS. Bodleian, 68 (S. C. 2142), c. 1390. 



69. Volvellae solis et lunae. 



f. 31, MS. Digby, 167. 



70. Volvelle. 1424. 

 Parchment in perfect order. Diameter 5^ inches. 



MS. Ashmolean, 370, f. 25. 



71. Volvelle. c. 1440. 



MS. Ashmolean, 191, ff. 53**, 199, 211. 



72. Volvelle (unfinished). 14 



MS. Ashmolean, 369, f. i b . 



73. Volvelle. 



Parchment. Diameter 5 inches. MS. Ashmolean, 789, f. 363. 



Perfect. Coloured, red, blue, and gold. 

 On the same page as a Zodiac man. 



74. Volvelle. Edw. IV. 



MS. Ashmolean, 1448, f. 278. 



75. Volvelle. 1460-62. 

 Coloured parchment. Diameter 6 inches. MS. Ashmolean, 391, f. 7. 

 The two pointers are marked volvella lune and volvella solis. The 



rule is written on the upper moveable circle in a spiral direction from 

 the edge to the centre ; beg. Pone volvellam solis. 



76. Volvellae lune et solis. i5th cent. 

 Diameter 4! inches. MS. Digby, 48, f. 203. 



77. Volvelle. 15. 



MS. Ashmolean, 1483, f. 77**. 

 Constructed to illustrate a work by Raymond Lully. 



Planetary Volvelles. 



Volvelles designed to illustrate the motions of the Planets are occa- 

 sionally found in astronomical treatises. An example of such a plane- 



1 Cf. Gemma Frisius, Cosmogr., fol. 50, ed. 1545. 



