OP THE MICROSCOPE. 129 



examine. To avoid this difficulty, the author, instead of insert 

 ing the pin of the forceps in the stage, provides a special for- 

 ceps-carrier like that shown in Fig 27. This consists simply of 

 a metal plate, the size of an ordinary slide, and having a hole in 

 one end to receive the pin of the forceps. A large hole is 

 pierced through the centre, to allow the passage of light from 

 the mirror when that is needed. This plate is placed on the 

 stage like a common slide, and it can be moved with as great 

 delicacy as any ordinary object. The mode of using it is too 

 obvious to require further explanation. We have found it ex- 

 ceedingly convenient. 



Object-Holder. The importance of being able to present 

 an object to the light in all directions is well-known to every 

 microscopist. Many years ago we devised an object-holder for 

 effecting this, the construction of which is very simple and in- 

 expensive. It consists of a slip of metal, the size of an or- 

 dinary slide three inches by one having a hole in the centre 



Fig. 28. OBJECT-HOLDER. 



and a short pillar rising from one end, as shown in the en- 

 graving, Fig. 28, which gives a sectional elevation of the 

 instrument. Through this pillar runs a wire, carrying at one 

 end a milled head by which it may be turned, and at the other 

 a ring which holds a perforated block. This perforated block 

 has a milled collar on the lower end, so that it can be readily 

 turned in the ring that carries it. The hole passing through 

 the block is just the size of a stout pin, so that a disk of card 

 or leather, with a pin through it, will be held steadily when 

 the pin is inserted in the hole. The object to be examined is 

 attached to the surface of the card, by means of balsam or mu- 

 cilage, and it is obvious that by the combined rotations that 

 may be produced by the two milled heads mentioned, it may 

 be exposed to the action of the light in any desired manner. 



