1.... :. . 



. ON COMPARATIVE MICROMETER MEASURES. 



IN A LETTER 



FROM. THE REV. DR. J, A. HAMILTON, DEAN OF CLOYNE, 



TO THE REV. J. BRINKLEY, F. R. S. 



■ '■ • '-'l '■ ■ 

 /.i'jfiio'j '/(!':.•.. 



„_, . ♦, ^x^ • *^*°» ^^8- 4'^ 1805. 



Jill '!o laia-iiil OflJ yd ■)br;;f?^^.^^^'*^''^''^"*'^' armach, jan. lo, 1805, 

 Jl.BEG leave,, through you, to communicate to our Aca- 

 demy the following paper, on comparative observations 

 made with different kinds of mici'ometers; which, I hope, 

 may be. deemed Avorthy their notice. It Avas suggested to 

 meii sd long since as in the year 1794, that a comparative 

 view of the result of the measures, made under similar cir- 

 cumstances, of the diameters of. the heavenly bodies, with 

 the dilierent kinds of micrometers, that are now most gene- 

 rally used byasti^onomera, might have considerable use; as 

 well iiL.confijTming the determinations of the values of the 

 diameters,, as, given by former observations, as in deciding 

 oil ;the, merits of the different instruments, and shewing, at 

 oae view,;, ai. sort )of haitoony of micrometers. My own opi- 

 aian, on. this sub|ect, entirely coinciding with that of the 

 learned friend, who made, this proposal, I set about making 

 comparative obseuvations of the measures of the sun's dia- 

 .TODDt X. • p meters, 



