2 The Microscope. 



on these points was collected ; and to convey it in 

 a simple manner to others is my present object. 

 There is also another kind of information of which 

 I was at the outset made personally independent, by 

 the possession of an excellent microscope, chosen, 

 indeed especially bespoken, by an unusually com- 

 petent judge of such a matter but which I have 

 endeavoured to obtain for the sake of others ; I mean 

 as to what points are especially worthy of attention 

 in the choice of a microscope, and what luxuries in 

 its apparatus can be dispensed with, with a view to 

 obtain a sufficiently good instrument at a low price. 



To convey this information, a few words on micro- 

 scopes in general are desirable. These instruments, 

 however various in their details, are made on just two 

 different plans the simple and the compound. An 

 explanation of the principle of each will presently be 

 given ; meanwhile, it will be sufficient to state that a 

 compound microscope has a long tube, and at least 

 two glasses, one near each end of the tube, while the 

 latter has no tube, and may have only one lens. 



Reading-glasses, hand- magnifiers, and Coddington 

 lenses, are, in principle, simple microscopes, though 

 that name properly belongs to those only which have 

 a fixed stand : of this class is the smart-looking little 

 instrument which is represented at No. 1, A, screwed 

 on to the lid of the mahogany box, into which ifc 

 packs nicely when not in use. The hand-magnifier, 

 B, is the simplest of all simple microscopes : it con- 

 sists merely of one lens, in a tortoise-shell frame, 

 made to shut up between two other plates of the same 



