ON DIVIDING ASTRONOMICAL INSTRUMENTS, 1 )3 



matp of the time, Avhich the different methods of dividing saved by it. 



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



are well employed in dividinj^- such a circle by my melhod; 



about fifty-two days would be consumed in doing- the same 



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



\Ahen 1 state the method by adjustment, supposing every 



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



to require about one hundred and tifty of such days. 



The economy of time (setting aside the decided means 

 of accuracy) which tiie above estimate of its . application 

 offers to view, will, I think, be considered of no tittle mo- 

 ment. By the rising artist, who may aspire to excellence* 

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

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

 means of effecting this became indispenslbje; and it has not 

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

 been urged to the piogressive improvement and completion 

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

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

 occasions, even in frames of firmer texture than my own, 

 that he can decisively command their adequate, unerring, 

 use. And I must confess, that I never could reconcile it 

 to what I hold as due to myself, as well as to a solicitous 

 regard for the most accurate cultivation of the science of 

 astronomy, to commit to others an operation requiring such 

 various and delicate attentions, as the division of my instru- 

 tnents. 



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, 1 have to reflect on with gratitude and pleasure: and 

 as I look wiih confidence to the continuance of that patron- 

 age, so long as the powers of execution shall give me the 

 inclination to solicit it, [ cannot entertain a motive, which 

 might go to extinguish the more liberal wish of pointing 

 out to future ingenuity a shorter road to eminence ; suffi- 

 ciently gratified by the idea of having in the present com- 

 munication contributed to facilitate the operations, and to 

 aid the progress of art (as far as the limited powers of vision 

 will admit) toward the point of perfection. 



Vol. XXV,-.Feb. 1810. I TahU 



