40 



THE MICROSCOPE. 



accuracy and steadiness bj the unassisted hand, bnt 

 must be mounted in a frame, having a rack or screw 

 to move it towards or from another frame or stage 

 which holds the object. It is then called a micro- 

 scope ; and it is furnished, according to circumstances, 

 with lenses and mirrors to collect and reflect the light 

 upon the object, with other conveniences. 



The best of the kind, contrived by the late Mr. Boss, 

 |g represented in fig. 24; and consists of a circular 



foot e, from which 

 rises a short tubular 

 stem d, into which 

 slides another short 

 tube c, carrying at 

 its top a joint /; to 

 this joint is fixed a 

 square tube a, through 

 which a rod b slides ; 

 this rod has at one 

 end another but 

 smaller joint g, to 

 which is attached a 

 collar h, for receiving 

 the lens i. By means 

 of the joint at /, the 

 square rod can be 

 moved up or down, so as to bring the lens close to 

 the object ; and by the rod sliding through the square 

 tube a, the distance between the stand and the lens 

 may be either increased or diminished : the joint g, 

 at the end of the rod, is for the purpose of allow- 

 ing the lens to be brought either horizontally or 

 at an angle to the subject to be investigated. By 

 means of the sliding arm the distance between the 

 table and the jointed arm can be increased or dimin- 

 ished. This microscope is provided with lenses of 

 one-inch and half-inch focal length, and is thereby 

 most useful for the examination and dissection of 

 objects. It is readily unscrewed and taken to 

 pieces, and may be packed in a small case for the 

 pocket. 



FIG. 24. Boss's Simple Microscope. 



