On dividing Instruments. 1 75 



adjustment is still iiiore expensive, requiring whatever tools 

 Bird's method requires, and, in atldilioii to these, a frame 

 and microscopes, sunieuhat siiiiilar to those for dividintr 

 by the eye. 



It is somewhat more difficult to give a com[)arstive esti- 

 mate of the time which the different methods of dividinc" 

 require. I know that thirteen days of eight hours each are 

 well employed in dividing such a circle by my method ; 

 about fifty-two dax'S would be consumed in doing the same 

 thing by Bird's method ; and I think I cannot err much 

 when I state the method by adjustment, supposing^ every 

 dot to be tried, and that two-thirds of them want adjusting, 

 to require about one hundred and fiftv of such days. 



The ceconomy of time (setting aside the decidid means 

 of accuracy) which the above estimate of its application 

 offers to view, will, I think, be considered of no little 

 moment. By ihe rising artist vvho mav aspire at excellence, 

 it will at least,- and I should hope, with gratitude, be felt 

 in the abbrtviation of his labours. To me, indeed, the 

 means (<f effectinsr this became indispensable; and it has not 

 been without a sufficient sense of its necessity, that I have 

 been urged to the progressive improvement and couijiletiou 

 of these means, as ^now described. It it but little that a 

 man can perform with his own hands alone ; nor is it on 

 all occasions, eveii in frames of firmer texture than my 

 own, that he can decisively command their adequate, un- 

 erring, use. And I must confess that I never could recon- 

 cile it to what I hold as due to myself, as well as to a soli- 

 citous regard fur the most accurate cultivation of the science 

 of astronomy, to commit to others an operation rcquirinir 

 such various and delicate attentions, as the division of my 

 instruments. 



That my attentions on this head have not failed to pro- 

 cure for me the notice and patronage of men whose appro- 

 bation makes, with me, no inconsiderable part of my re- 

 ward, I have to reflect on with gratitude and pleasure : and 

 as I look with confidence to the continuance of that pa- 

 tronage so long as the powers of execution shall give me 

 the inclination to solicit it, I cannot entertain a motive 

 v\hich might go to extinguish the more liberal wish of 

 fjointing t)ut to future ingenuity a shorter road to eminence j 

 sufficiently gratified by the idea of having, in the present 

 communication, contributed to facilitate the operations, 

 and to aid the |irogress of art (as far as the limited po Wei's 

 vf vision will admit) towards the point of perfection. 



Taile 



