182 



MICROSCOPIC OBJECTS, 



candle-holder, large condenser and shade, when required. 

 The annexed engraving represents the same microscope 

 in a horizontal position, with the stage turned a quarter 

 round, so that open vessels of water of any depth con- 

 taining small fish, insects, zoophytes, or aquatic plants. 



can be examined without removal. This engraving also 

 shows the manner in which a camera lucida, attached to 

 the eye-piece a, is used in drawing objects under the 

 microscope. The same letters employed in the engra\Tng 

 in page 1 80 represent similar parts in this figure, o is the 

 milled head for giving a fine adjustment to the focus, 

 which for high magnifjang power and the examination of 

 dehcate tissues is a necessary addition, t represents the 



