36 



PREPARATION AND MOUNTING 



Mr. Spencer slightly modifies the above, using wood 

 jaws and wedge, which the following engraving will best 

 explain. 



DR. MATTHEWS' TURNTABLE, TWO-THIRD SIZE. 



Many objects for the microscope may be seriously injured 

 by allowing the fingers to touch them many more are so 

 minute that they cannot be removed in this way at all, and 

 often it is necessary to take from a mass of small grains, as 

 in sand, some particular particle. To accomplish this, there 

 are two or three contrivances recommended : one by means 

 of split bristles, many of which will readily be found in 

 any shaving-brush when it has been well used. The bristles 

 when pressed upon any hard surface, open, and when the 

 pressure is removed close again with a spring ; but the use 

 of these is limited. Camel-hair pencils are of great service 

 for this, and many other purposes, to the microscopist. 

 Tn very fine work they are sometimes required so small that 

 all the hairs, with the exception of one or two finer pointed 



