OBSERVATIONS ON THE METALLIC COMPOSITION 



FOR 



THE SPECULA OF REFLECTING TELESCOPES, 



AND THE MANNER OF CASTING THEM: 



Also a melhod cf cdmmtinicating to them any particular conoidal figure : with 



an attempt to explain, on scientific principles, the grounds of each 



process : and occasional remarks on the construction of telescopes. 



BY THE REV. JAMES LITTLE. 



READ, FEB. 4"", 1805i 



1 HERE are but few things produced by the united effort 

 of mechanical artifice and intellectual labour, which have 

 done more honour to the ingenviity and invention of man, 

 than the reflecting telescope; which has many advantages 

 over any of the dioptrical kind, notwithstanding their im- 

 provement by achromatic glasses. It Avill bear a greater 

 aperture, and may be made to magnify more, (as being more 

 distinct,) in proportion to its length, than the others, as 

 they are at present made; and its dfmensions and powers 

 are unlimited. What its excellence is, especially the New- 

 tonian 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 labours. Accordingly, the 

 persons, eminent for science and mechanical ingenuity, ap- 

 pear to have felt a peculiar and disinterested pleasure, in 



Q 2 contributing 



