236 LANKESTER, ON A MUSLUM MICROSCOPE. 
moved by the aid of a screw-driver. This secures the 
immovability of the eye-piece. As a matter of experience, 
I may state that the screw needs to be very strong, as persons 
having a little knowledge of the microscope, and wishing 
to display it, have made violent efforts to remove the eye- 
piece, which of course 1s intended to be fixed. The object- 
glass, d, is attached to the tube, and is also secured by the 
aid of ascrew. Thus the only movement permitted to the 

Fig. 1. 
tube of the instrument is performed by a screw, e, which 
moves the tube in the way of the fine-adjustment of the 
ordinary microscope. As moveable slides would be liable to 
accident or to be purloined, two forms of slide which are 
not removeable from the microscope have been supplied. 
These are fixed in the position usually occupied by the stage, f. 
The slide for transparent objects is circular, and is made of 
wood, and has holes bored for the reception of eight pieces 
of glass on which the object is placed. A piece of thin 
glass is then put over this, and the whole kept in position by 
an elastic metallic ring. The slide revolyes on a metal 
