174 Record of the Royal Society. 



1 9. A brass standard of Length, marked 



Exch r . Standard, Hen. VII. 1490. 

 Exch r . Standard, Eiiz. 1588. 



20. Trigonometer, by Bowles. 4 parts. 



21. Repeating Circle, of one foot diameter, by Troughton. 



Employed by Captain Kater at the principal Stations of the Trigono- 

 metrical Survey. ' Phil. Trans.,' 1819, p. 339. 



22. Chronometer, by Arnold. 

 28. Chronometer, by Arnold. 



Both these Chronometers accompanied Captain Cook on Ids second and 

 third Voyages. 



24. A 12-inch Dipping Needle, by Nairne and Blunt. 2 parts. 



' Phil. Trans.,' 1776, p. 395. 



25. A 12-inch Variation Needle. Ibid., p. 385. 



26. A Magnetic Variation Needle, with Vernier Microscopes, by 



Jones ; for making observations 011 the influence of the Aurora 

 Borealis upon the Magnetic Needle. 



27. Dr. Gowin Knight's Battery of Magnets. Presented to the Royal 

 Society by Dr. John Fothergill in 1776. 



Re-arranged in 1828 by Captain Beaufort and Mr. Barlow. 



28. Armed Loadstone. 



Grew's ''Catalogue of Rarities" (p. 364) mentions an Orbicular Load- 

 stone, or Ter[r~]ella, given by Sir Christopher Wren, the size of 

 which, so far as the stone is concerned, agrees with the above ; it is 

 conjectured that it may be the same. 



21). A Galvanic Battery, made by Dr. Wollaston, in a tailor's thimble. 

 Presented to the Royal Society by Sir A. W. Franks, June 28, 1879. 

 In a letter to the late William Spottiswoode, P.R.S., which accompanied 

 this present, Sir (then Mr.) Augustus Wollaston Franks says that 

 this little battery was given by his godfather, Dr. Wollaston, to 

 his mother then Miss Sebright. See also an anecdote about this 

 battery in Weld's ' History of the Rojal Society,' vol. 2, p. 309. 

 30. Dr. Priestley's Electrical Machine. 



81. Curioun Steel Callipers for very accurate measurement, by Paull 



of Geneva: 1777. 



82. Rowning's Universal Constructor of Equations. 



' Phil. Trans.,' 1770, p. 240. 



83. The original model for Davy's Safety Lamp. 



And other Instrnments of less interest. 



