MICROSCOPIC OBJECTS. 205 



augmentation of the height of that part of the apparatus 

 which carries the object to be viewed will become 

 necessary. Tlie table (i, fig. 4) must now be placed in a 

 vertical position, with the mirror (g) uppermost, which is 

 effected by putting the pin under the said table into the 

 horizontal hole in the ball. The right elevation wiU be 

 obtained by removing the pin (g, fig. 6) from the pillar 

 {b, fig. 4) and inserting the stilt or lengthening piece 

 (fig. 8) between them, which must accordingly be made 

 of the requisite length. 



For such as may still be dissatisfied with these modes 

 of observing, who reject the use of plane mirrors and 

 prisms in any form in the optical part of the instrument, 

 and are content with using the instrument horizontally 

 or at an angle of 45°, the apparatus represented in fig. 4 

 is more particularly contrived. It is so made that when 

 the body is inclined at an angle of 45°, and the rod (m, fig. 1 ) 

 as low down as it will go, the stage will be at right angles 

 to the optical part, and its centre adjusted to it ; at least it 

 can be veiy readily made so to be, by levelhng the body in 

 the direction of a fine drawn from one end of the table 

 to the other. Its construction is so simple, that its 

 appearance ought to explain it ; except perhaps that of 

 the muTor, which I shall therefore describe, g is the 

 mirror in a strong but light wooden frame, having the 

 back pretty thick and firmly screwed on, and moreover 

 strengthened in the middle by a plate of brass carefully 

 fixed on. This mirror is attached to the stand by 

 means of a hinge, which is shown at fig 9 of half the real 



