30 



fi-EFLEdl^TG tELESdOi^S. 



to be seen in the registry of observations kept at the Observa^ 

 tory, Armagh, for the years 17 94 and 1795. 

 I have the honour to be. 

 Dear Sir, 

 Your faithful and obedient Servant, 



JAMES A. HAMILTON, 



Observations on the Metallic Cojnpositionfor the Specula of refect- 

 ing Telescopes, and the manner of casting the7n : also, a Me' 

 thod of communicating to them any particular Conoidal Figure i 

 with nn Attempt to explain on scientific Principles, the grounds 

 of each Process: and occasional Remarks on the Construction 

 cf Telescopes. By the Rei\ James Little * 



„.Ti 



Excellence of A HERE are but few things produced by the united effort 

 the Reflecting of mechanical artifice and intellectual labour, which have done 



7*^16 SCO DC 



more honour (o the ingenuity and invention of man, than the 

 reflecting telescope; which has many advantages over any of 

 the dioptrical kind, notwithstanding their improvement by 

 acromatic glasses. It will bear a greater aperture, and may 

 be made to magnify more, (as being more distinct,) in propor- 

 tion to its length, than the others, as they are at present made ; 

 and its dimensions and powers are unlimited. What its excel- 

 Particularly the lence is, especially the Newtonian construction of it, has been 

 proved by Dr. Herschell, to his own honour, and that of the 

 age, and country, and patronage, which encouraged his la- 

 bours. Accordingly, the persons, eminent for science and 

 mechanical ingenuity, appear to have felt a peculiar and disin- 

 terested pleasure, is contributing to its improvement: and the 

 late discovery of a metallic composition for the mirrors of it, 

 which will bear as high a polish as glass, reflect as much light 

 as glass transmits, and endure almost equally well, without con- 

 'tracting tarnish, is a farther encouragement to prosecute its 

 improvement to perfection. 



* Irish Transactions, Vol. X. 



