110 THE MICROSCOPE. 



tube in or out. The object, if transparent, is illuminated 

 either by holding up the microscope towards a white cloud, 

 or other source of light, or by directing it towards a mirror 

 laid upon the table at such an angle as to reflect the light. 



Fig. 64. — Highley's Pocket Microscope. 



If opaque, it is allowed to receive direct light through an 

 aperture in the outer tube. The extreme simplicity and 

 portability of the instrument — which is only six inches 

 long — constitutes its chief recommendation. 



Norman's (178, City Eoad) Universal Educational 

 Microscope consists of a well-finished stand with tripod 

 foot and two uprights, with axis for giving inclination to 

 the optical part. The body has quick and slow motions, 

 one Huyghenian eye-piece, three achromatic object-glasses, 

 viz. a •j-inch dividing into \ and 1 inch, all of fair de- 

 fining power and English made. The stage has a large 

 sliding-piece, and a revolving wheel of diaphragms ; the 

 mirror has sliding and oblique motions for the better illu- 

 mination of the object under examination. The following 

 apparatus is also supplied with the instrument : — a stand 

 condenser with adjustment, stage and hand forceps, live- 

 box or anirualculae cage, a frog-plate for viewing the circu- 

 lation of the blood in the web of a frog's foot ; also three 

 good objects to test the different object-glasses, one hol- 

 lowed and two plain slips, some thin glass. The whole is 

 packed in a mahogany or walnut cabinet, with a drawer 

 for objects, lock and key, and sold for the small price of 

 3/. 5s. 



24 first-class objects, suited for the object-glasses, are 

 supplied with this instrument for 11. Is. 



Mr. E. Wheeler's (Holloway) well-made instruments de- 

 serve commendation and notice; they are carefully finished 

 and quite up to the modern standard. The full assorted 

 sets of objects which Mr. Wheeler supplies in a very neat 



