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public find that a body of scientific men, invested with an 
unusual power, are either unable or unwilling to use it for 
the public good. 
“ On the Casting, Grinding, and Polishing of Specula for 
Reflecting Telescopes,” Part III., by James Nasmyth, Esq., 
C. E., Corresponding Member of the Society. 
The author in this part of his paper describes in consider- 
able detail the methods he employs in casting, grinding, 
polishing, and giving perfectly fiat surfaces to the plane 
mirrors of reflecting telescopes. 
i . 
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