4 MATHEMATICAL INSTRUMENTS. 



lay neglected and out of order in the Tower, at London, and Sir Jonas Moore 

 . j f begd it of his present majestic, who showed it to me.' Aubrey's Lives. 

 i*** 1 5. Three Spheres. Boxwood. 



t \:\ ""/'{ pfam.eier -^-inches. Orrery Coll. 5. 



Marked in ink to illustrate propositions on spherical triangles. 

 Two of the spheres are supported in turned wooden pedestal cups. 



6. Abacus. 



Size about 14 inches x 4^ inches. / 



? Rawlinson Bequest. Charter Case, Drawer 38. Bodleian Library. 



7. Napier's Bones. c. 1730. 



In boxwood case, 3^ inches x 2-f- inches. Ashmolean Museum. 



For multiplication and division on the system invented by John 

 Napier of Merchiston (1550-1617). 



DRAWING INSTRUMENTS. 



' The Making of good Mathematical Instruments is almost peculiar 

 to the English ' (Stone, 1758). 



8. Set of Drawing Instruments. 



In flat case. By Rowley. Orrery Coll. (34). 



Silver with chased decorations. The set includes a pair of 6|-inch 

 compasses, with pen, pencil-holder, and dotting wheel ; 5-inch dividers ; 

 ruling pen; turnscrew; and a long ruling pen that may belong to 

 a different set. 



9. i3-inch Compasses. 17 . 

 Wood and iron (broken). Oriel College. 



10. Proportional Compasses. 



Silver with steel points. Orrery Coll. (20). 



Inscr. : John Rowley Londini Fecit. 



11. Four-sided Scale with Compasses in one end and a Pencil-holder 



in the other. 



Silver, 6 inches in length. In original case. Orrery Coll. (21). 



Inscr. : I. Rowley Fecit. 



12. Parallel Rulers. 



Ebony, 7 inches long. Orrery Coll. (46 a). 



Cf. Stone's Bion, PI. X, Fig. R. 



Protractors. 



13. Rectangular Protractor. 



Ivory, 6 inches. Orrery Coll. (46 b). 



Inscr.: I. Rowley Fecit. 



With a scale of ^th of an inch along one edge, 



