THE SIMPLE MICROSCOPE. 



55 



fixing, and the magnifier itself can be taken off or put on with 

 the greatest facility. 



Mr. Eoss has contrived a small but exceedingly useful in^ 

 strument, answering the same purposes as the preceding; it is 

 represented by fig. 34, and consists of a circular foot, e, about 



Fig. 34. 



an inch and a half in diameter, from which rises a short 

 tubtdar stem, d, into this shdes another short tube, c, carrying 

 at its top a joint, f;to the joint is fixed a square tube, a, 

 through which a square rod, b, slides; this rod has at one 

 end another but smaller joint, ff, having attached to it a lens 

 holder, h. By means of the joint at f, the square rod can be 

 moved up and down, so as to bring the lens close to an object, 

 or remove it from it, and by the rod sliding through the square 

 tube, a, the distance between the stand and the lens may 

 either be increased or diminished ; the joint, ff, at the end of 

 the rod, is for the purpose of allowing the lens to be brought 

 either perfectly horizontal, or to be inchned at any angle with 

 the subject to be investigated. By means of the sliding tube, 

 c, the distance between the table and the jointed arm can be 

 'increased or diminished. This microscope is provided with 



