The Use of a Simple Microscope. 



17 



bat where, as In the case of the above textile materials, no two 

 pieces can be found sufficiently similar in outline to be mis- 



Fig. 12. — a. Cjcoa-nut coir. h. Ejoo. ^^ 



taken for each other, or where substances are broKen up Into 

 irregularly formed masses, these require to be studied with regard 

 to the general form and character of the masses ; as, for instance, 

 whether they possess angular or rounded edges, or any particular 

 direction for breaking up, or whether they are rough or smooth, 

 dull or shining in the fracture, opaque or transparent. All or any 

 one of these features may constitute the distinctive characters of a 

 given substance, therefore particular attention should be directed 

 to them ; and, when these have been determined, diagrams may 

 be employed to assist the memory ; but it Is very desirable that 

 the objects themselves should be preserved for future examina- 

 tion and reference. 



The IMagnifytng Glass or Microscope. 



The construction of the magnifying glass, or microscope, varies 

 according to the use for which it is intended ; but the essential 

 part consists of a highly polished piece of very clear glass, termed 

 *■' a lens," which has one or more curved surfaces ; an ordinary 

 spectacle glass may be taken as the simplest form of a common 

 magnifier of very low power : a sphei-e of glass, or of any other 

 transparent substance, being the highest magnifier that can be 

 obtained by one single piece. Thus, the more convex it is, the 

 shorter Is its focus', or in other words, the closer must the object 

 and the eye be placed, to obtain a distinct vision, and conse- 

 quently the more the object is magnified. The perfection that 

 has been of late years attained in the construction of the microscope 



VOL. III. — S. S. C 



