18 Modern Microscopy. 



Although good second-hand instruments may be occasion- 

 ally met with, great discretion is required in purchasing, 

 owing to the improvements that have been introduced in 

 the first place, and that some damage may have occurred to 

 the optical parts in the second place. If it be obtained from 

 a respectable dealer who understands his business and will 

 give a guarantee of condition, there is some inducement ; 

 but a friend who is up to date in microscopy is generally 

 the best to advise. In all cases, before purchasing, a cata- 

 logue should be obtained from the maker whose name the 

 instrument bears, so that it may be ascertained whether the 

 pattern is still made or is antiquated and out of date. It is 

 much better to buy a good stand capable and worthy of 

 receiving additional apparatus from time to time, rather 

 than a complete cheap instrument. These latter rarely 

 engender pride of ownership, and are often relegated to 

 some obscure corner after a short acquaintance ; whereas if 

 a good instrument be purchased, with even only one objec- 

 tive to start with, there is always a pleasure in working with 

 it, and a peculiar fascination from its quality a satisfaction 

 in feeling that one has something superior. 



There are several very cheap microscopes on the market, 

 and although it is sometimes claimed that they foster the 

 scientific spirit and educate the microscopical beginner, it is 

 very doubtful whether they do not do more harm than good 

 from dissatisfaction with their performance on comparison 

 with those of superior make : possessors of such become dis- 

 heartened, often attributing want of success to themselves, 

 and not to the instrument. 



To make the different parts quite clear, on page 17 is 

 figured a student's microscope, of which the following is a 

 description : 



FIG. 2. A is the stand or foot. 



B is the tailpiece carrying the mirror (C) with which light 

 is thrown upon the object. 



D is the under-fitting, into which are fitted the sub-stage 

 condenser, polarizer, etc. 



