CH. IX] PROJECTION MICROSCOPES ON THE MARKET 305 



Commencing at the left : 



Large, well ventilated, light-tight lamp-house. As shown in fig. 104, 105, 

 the lamp-house with the lamp and first element of the condenser can be inclined 

 to direct the light downward upon an opaque object. 



Following the lamp-house is a dark box for opaque projection. The large 

 projection objective with mirror is above and the table for the opaque objects 

 below. Within the dark box is a mirror so inclined that it reflects part of the 

 scattered light back upon the object (see also fig. 105). Opaque objects up to 

 20 cm. (8 in.) square can be projected. 



Following the large objective for opaque projection is an objective for lantern- 

 slide or other projection with the object in a horizontal position. Following 

 this is the polarizing apparatus of glass plates (see 880). The second element 

 of the condenser serves for lantern-slide and for low power micro-projection, 

 but for high powers this is turned out as here shown and a small double convex 

 lens in the dark chamber near the first element of the condenser is swung into 

 position and serves to project an image of the crater at the plane of the dia- 

 phragm of the substage condenser (fig. 170). 



Just beyond the bellows are shown the projection microscope and the 

 lantern-slide objective. These are so hinged parallel to the axis that the 

 microscope can be turned laterally and thus bring the lantern-slide objective in 

 position. In the picture the lantern-slide objective is turned aside and the 

 projection microscope is in position. 



The substage condensers for different objectives are shown on a revolving 

 carrier, as are also the micro-projection objectives and the projection ocular 

 and amplifier. 



FIG. 170. DIAGRAM OF THE ILLUMINATING SYSTEM FOR HIGH POWER 



PROJECTION. 

 (Cut loaned by the Bausch & Lomb Optical Co.}. 



This is a modification of the Kohler system ( 401-403), and consists of the 

 first element of the triple condenser (meniscus and convex lens) to render the 

 beam parallel. The small, convex lens near the condenser serves to project 

 an image of the crater upon the plane of the diaphragm of the substage con- 

 denser. This is designed to fill the aperture of the substage condenser and, 

 hence, of the high power objectives. 



L The radiant. 



C The meniscus and convex lens of the condenser and the small special 

 convex lens for micro-projection. 



L' Inverted image of the radiant. 



E Substage condenser. 



5 The specimen. 



C' Image of the small condensing lens in the plane of the specimen (5). 



