1 94 PROJECTION OF IMAGES OF OPAQUE OBJECTS [CH. VII 



zontal position the image will only be erect with the screen at right 

 angles to the axis of the objective, no mirror or prism being used. 

 If a mirror or prism is used to project upon a vertical screen then a 

 translucent screen will give a mirror image, but an opaque screen 

 an erect image. 



FIG. 109. DIAGRAM FHOWING THE PARTS AND COURSE OF THE RAYS IN* 



MODEL 4-5 DELINEASCOPE. 

 (Cut loaned by the Spencer Lens Co.). 



This diagram shows the arc lamp and first element of the condenser in posi- 

 tion to illuminate a vertical object in opaque projection. Above is shown in 

 outline the course of the rays for the projection microscope or the magic lantern. 



Commencing at the left : 



OH The object holder for objects 15 x 23 cm., 6x9 in. 



II Handle for operating the object holder. 



X The horizontal axis on which rotates the arc lamp and the first element 

 of the condenser. 



OO The large projection objective for opaque objects. 



WC Water-cell for removing the radiant heat. 



ID Large iris diaphragm. 



L Lantern slide, and crank for turning the slide up in the vertical position 

 in front of the condenser behind the objective. 



P Platform on which is laid the lantern slide. 



LO Lantern-slide objective turned to one side to allow the microscope to 

 get to the horizontal position. 



M Mirror to reflect the horizontal beam of light through the vertical 

 microscope. 



