JOURNAL 



OF 



NATURAL PHILOSOPHY, CHEMISTRY, 



AND 



THE ARTS. 



JANUARY, 1810. 



ARTICLE I. 



An Account of a Method of dividing Astronomical and other 

 Instruments, hy ocular Tnspeciion ; in tvhic/i the iifital Tools 

 for graduating are not employed ; the whole Operation be- 

 ing so contrived, that no Errour can occur hut ivhat is 

 chargeable to Vision, when assisted hy the best optical 

 Means of viewing and measuring minute Quantities. By 

 Mr. Edward Troughton. Communicated by the Astro- 

 nomer Royal*. 



I 



T would ill become me, in addressing myself to the D{v;5;on of as- 

 members of this society upon a subject which they are so troaomical ia- 

 well enabled to appreciate, to arrogate to" myself more than 

 may be assigned as my due, for whatever of success may 

 have been the result of my long continued endeavours, ex- 

 erted m prosecuting towards perfection the dividing of In- 

 struments immediately subservient to the purposes of astrono- 

 my. A man very naturally will set a value upon a thing, 



* Philos. Trans, for 1809, p. 105. 



A^oL. XXV— No. 111. Jan. 1810. B ©n 



