SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



PART OF VOLUME XXXIV 



ON THE MODERN REFLECTING 



TELESCOPE, AND THE MAKING AND 



TESTING OF OPTICAL MIRRORS 



BY 



GEORGE W. RITCHEY 



ASSISTANT PROFESSOR OF PRACTICAL ASTRONOMY, AND SUPERINTENDENT OF INSTRUMENT 

 CONSTRUCTION, IN YERKES OBSERVATORY 



(No. 1459) 



CITY OF VVARinXGTON 

 rUIJLISHEI) BY TIIK SMITHSONIAN INSTITUTION 



1904 



