96 PRACTICAL TREATISE ON THE MICROSCOPE. 



SO as to suit every piirpose. For convenience of package, or 

 for applying Mr. Varley's graphic eye-piece to this instru- 

 ment, the compound body and its supports, 7, may be 

 removed from the rod, d, and the rod itself may be drawn out 

 of the tube, z, so as to allow of any object not more than three 

 inches thick being examined under a lens of two inches focus. 

 Amongst other advantages in this microscope, there is added 

 to it a small piece of apparatus, by which a phial having 

 chara growing in it, or animalcules adhering to its' inner sur- 

 face, may be examined in a vertical position : many of these 

 last would, in all probability, be shaken off if the phial were 

 turned about when inclined. Also, by the addition of the 

 graphic eye-piece, the tracing of aU kinds of objects, whether 

 magnified much or little, can be readily accomplished. The 

 price of this microscope, exclusive of the object-glasses, varies 

 from £20 to £30. Another very excellent form of micro- 

 scope is that constructed by Mr. Dancer, of 43, Cross-street, 

 Manchester; it is represented by fig. 48, and consists of a 

 firm tripod of brass, from which rise two stout pUlars, bearing 

 at their upper extremities the trunnions that support a slightly 

 curved arm, to which the stage and compound body are at- 

 tached, somewhat after the plan of that of Mr. George 

 Jackson. The compound body itself consists of two tubes, 

 the outer one being attached to the arm by two saddle-pieces 

 with screws ; this tube is sprung at either end, and within it a 

 smaller one can be moved up and down by rack and pinion, 

 turned by a large mUled head ; this forms the coarse adjust- 

 ment, whereas the fine is effected by a plan of Mr. Hoss, 

 viz., by a lever attached to the small tube carrying the 

 object-glasses, which is moved either up or down by a fine- 

 threaded screw. The stage is about four inches long, and two- 

 and-a-half broad, and on it slides an object-plate longer than 

 the stage-plate, but about half its breadth. To the front of 

 the stage may be fixed the forceps and a large condensing 

 lens, if necessary. The mirror is of the usual form, and is 

 capable of being moved up or down the tube that connects it 

 with the under surface of the stage, and can also be inclined at 

 any angle. With this microscope, Mr. Dancer supplies the 



