Preparing for publication, in 8t;o. with Engravings, 

 THE OPT[CAL SECTION OF 



THE MICROGRAPHIA; 



OR, 



PRACTICAL ESSAYS ON SUCH IMPROVEMENTS IN MICROSCOPES AND 

 ENGISCOPES AS HAVE EITHER BEEN OMITTED IN THE " MICRO- 

 SCOPIC ILLUSTRATIONS," AND " CABINET," OR HAVE 

 ONLY BEEN BRIEFLY NOTICED. 



BY 



C. R. GORING, M.D. 



AND 



ANDREW PRITCHARD, Esq. 



CONTENTS. 



History and Description of the Amician Catadioptric Engi- 

 scope. — On Micrometers^ and their use in determining the 

 Foci and Powers of Object-Glasses, Metals, and Single and 

 Compound Magnifiers. — On Monochromatic Illumination. — On 

 the most improved Construction and Management of Solar and 

 Oxy-Hydrogen Gas Microscopes. — On Solar Engiscopes, and 

 the Exhibition of Tests by them. — On trying Microscopes 

 and Engiscopes against each other ; with Rules for ascertain- 

 ing their comparative Merits. — On the Spherical and Chro- 

 matic Aberration of Eye-Pieces. 



