PRACTICAL PHOTO-MICROGRAPHY. 49 



platform which turns or a central pivot, so that the optical 

 system can be turned out from the axial line of the entire sys- 



FIG. 15. PHOTO-MICROGRAPHIC APPARATUS BY SWIFT, SHOWN AT THE 

 VERTICAL POSITION. 



tern, the object can be examined, corrections of the objectives 

 studied, and everything focused and centered with the eye- 



