22 OCTANTS AND SEXTANTS 



BACK-STAFF 



100. English or Davis' Quadrant or Back-staff. 



Pitt-Rivers. 

 Name plate missing. 

 For use cf. Stone's Bion Math. Instr., p. 204. 



101. English or Davis* Quadrant or Back-staff. 



Pitt-Rivers. 

 Edm : Culpepper fecit. 



Pear-tree wood. Decorated with rose and fleur de lys stamps. 



OCTANTS AND SEXTANTS 



102. i8-inch Octant, with ivory scale and dark glasses and pin-hole 



sights. 17 . 



Oriel College. 



103. lo-inch Octant, ditto. 17. 



Pitt-Rivers. 



104. i6-inch Octant, ditto. With a pendent brass label marked E. 



17. 



Gunther Collection. 



105. 6-inch Sextant with pin-hole sights. 17 . 



Oriel College 

 63^ Jos. Jackson, London, No. 122. 



106. 6-inch Sextant with telescope in mahogany case. 17 . 



Oriel College. 

 By J. Dollond and Son, London. 



107. Circumferentor or Surveying Compass. Brass. c. 1690. 



Orrery Coll. 15. 

 /. W organ fecit. 



The base plate in a circle 13 inches in diameter, with a border 

 divided into \ degrees ; two slit and thread sights are carried at the o 

 and 180 marks. 



108. Graphometer or Surveying Semicircle. c. 1690. Q 



Orrery Coll. 50. 

 With Folding tripod stand 4! feet in height. 



109. Plane Table. I6g 6. 



Orrery Coll. 18. 

 13?: x io inches with Compass in a wooden bracket at one side. 



LENSES 



110. Large Burning Glass. I8 th cent. 



Chemical Department. 



There is nothing to show who was the maker of this large lens, but 

 it undoubtedly dates from the days of the old Ashmolean Laboratory. 



