THE MICROSCOPE. 2& 



on the cover of the cage without pressing the 

 fluid out at the sides of the cage. If the water 

 is thus allowed to overflow, it runs over the glasses 

 of the cage, and thus ohscures vision. An object 

 or objects having been thus placed in the cage, 

 it is conveyed to the stage, and placed in such 

 a position that the ray of light passing from the 

 mirror to the object-glass may pass through it. 

 This having been done, the observer must now 

 place his eye over the eye-piece, and use the 

 screw in the tube, and move the object-glass down- 

 wards until he gets a clear view of objects moving 

 in the water. This is called focussing. The glass 

 may then be moved up or down, in order that 

 the best view of the object may be obtained. 

 When the object-glass is one of high power, the 

 fine adjustment mav be used for this purpose. 

 When the proper focus is obtained, the object may 

 be moved up or down, right or left, with the hand, 

 or by the aid of the screws which are employed in 

 the various forms of what are called mechanical stages. 



When objects not requiring the live-box or 

 animalcule-cage are to be observed, they may be 

 transferred to the glass slide by aid of a thin slip 

 of wood, or a porcupine-quill moistened at the 

 end, or by a pair of small forceps. (Fig. 8.) Some 

 transparent objects may be seen without any me- 

 dium, but generally it is best to place them on the 

 slide with a drop or two of clean water, which may 

 be placed on it with a dipping-tube. When water 

 is used, it will generally be found best to cover the 

 object with a small piece of thin glass. Small 

 square pieces of thin glass are sold at all the 

 opticians' shops for this purpose. The object is 

 then placed under the object-glass as before. 



In order to render objects transparent, so that 



