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XIII. An Account of a Method of dividing astronomicdf 

 and other Instruments, ly ocular Inspection ; in ivliich 

 the Viitiul lOols for graduating are not employed; tlie 

 lihole Operation being so contrived, that no Error can oc- 

 cur hit u/liat is chargeable to Fision, when assisted ly the 

 best optical Means of viewing and measuring minute 

 Quantities. By Mr. Edwahd TkoughtOx\*. 



A Letter from Mr. Edward Troughton, Mathematical 

 Instrument \y,aker, to the Asironojner Royal f. 



f^^ SIP., London, June '23, ISO?, 



•J- HE science which you profess, and the art which it has 

 fallen to my lot to cultivate, are so nearly allied ; that, had 

 I been personally unknown to you, and a strancer to the 

 patronage which vou have always given to the useful arts, I 

 should still have wished the papers annexed to have passed 

 through your hands to the public. You will readily thence 

 infer, how much I ieel niysilf tlattcred by having obtained, 

 from your condescension, the privilege of their being pre- 

 sented to the Roval Society through a channel which must 

 secuic for ihem the most favourable recc[)tion. 



My reputation for the dividing of astronomical and other 

 instruments, is by no means unknown to ihe world ; but 

 the means by which I accomplish it, 1 have hitherto thouoht 

 proper to conceal : and if that concealir.ent had been essen- 

 tial to the advancing of that reputation, or to tnc immediate 

 security of my own interests, it is probable thf\t it miglit 

 still longer have rested with myself. Relying, however, ai 

 I do, on the probability that I shall find sutficient einploy- 

 ment while 1 am capable of active life, I know of no ho- 

 nourable motive that should prevent me from allowing it to 

 be use'ul to oihcif>. 



Kuw a young artist, who may just be beginning to make 

 his way to fame or wealth, mav receive it, i know not; but 

 I wish him to understatid, that I consider myself now in the 

 act of making him a very valuable present. 

 1 have the honour to he, sir, 



your obliged and obedient servant, 



£d\v. Tkouohton. 



To the Rev. Nt:viL Maskelvne, D D., 

 Astrononitr Rvyal, F.R.1>., &t. 



• From Pliilosophical Traiiiactions for 1809, Pari I. 



+ This Icrier is not inseiicil in the >-iic-it"iy's rraiisactions, but appears in 



the ccpics of the Paper circulated l>y the author iimong hfs private friends. 



iDir. 



y/<j\. 34. No. 136. August 1800. F Account 



