14 VIEWS OF THE MICROSCOPIC WORLD. 



is screwed into a circular aperture made in a thick piece of wood, and to the 

 wood on the opposite side a mirror is attached of a rectangular shape. When 

 the microscope is used, the mirror is thrust through an opening in a window- 

 shutter, and the piece of wood, with the attached tube and its lenses, firmly fas- 

 tened on the inside. All the shutters of the room being now closed, the mirror 

 is so adjusted as to receive the direct rays of the sun and reflect them along the 

 tube, where they are received by the condensing lens, which concentrates them 

 upon the object, placed a little farther from the object-glass than the principal 

 focus. 



The object being thus highly illuminated, the bright rays that proceed from 

 it and fall upon the object-glass converge and form a magnified and inverted 

 image upon the surface of a large screen, placed at a distance at the opposite 

 side of the apartment. 



In consequence of the powerful concentration of light upon the object, the 

 image may be distinctly seen by a number of spectators in various parts of the 

 room. The image is formed in the manner already described under figure 2, 

 where B L in this case would be the distance of the object from the centre of the 

 object-glass D E, and L G the distance of the screen. Thus if B L was one-tenth 

 of an inch in length, and L G twenty feet, the object would be magnified linearly 

 2400 times, and superficially 5,760,000 times. 



In this form of the solar microscope, transparent objects only can be. viewed ; 

 opaque objects may also be magnified, when their surfaces are rendered intensely 

 bright by the aid of special contrivances for concentrating the light upon them. 

 In place of the solar rays, the dazzling light caused by an ignited jet of hydro- 

 gen and oxygen gases playing upon carbonate of lime, has been advantageously 

 employed for this microscope, and the still more brilliant light produced by the 

 galvanic battery, when its poles are tipped with charcoal points. 



