THE COMPOUND MICROSCOPE. 41 



THE COMPOUND MICROSCOPE. The compound micro- 

 scope consists of two essential parts, the stanc 

 optical arrangement ; the first image being further 

 magnified by one or more lenses forming tHe eye- 

 piece. The mechanical principles involved in tte con- 

 struction of the compound instrument are feW and 

 simple. The more finished form of microscope has 

 assumed a degree of solidity and luxurious elegknce 

 heretofore unknown, whilst its accessories have multi. 

 plied to an almost unlimited extent. This has resulted 

 from a desire to save time or overcome difficulties, as 

 the practical skill and experience of the microscopisf 

 or optician may have suggested, so that whilst the- 

 wants of the amateur have been duly considered, tht- 

 more modest demands of the student have in no wa^ 

 been overlooked or forgotten. 



Fortunately for the student, no large and expensive 

 form of instrument is absolutely necessary for the 

 pursuit of microscopical science. A small and simple 

 microscope is as well adapted to his wants indeed is 

 all that he requires for the work he has to perform. 

 And as for his cabinet of objects, these will grow day 

 by day, and by the labour of his hands. It was with 

 a very unpretending form of microscope that John 

 Quekett worked ; that John Ralfs studied the " British 

 DesmidiaceaD ; " John Denny the " Anoplura ; " Wil- 

 liam Smith the " British Diatomaceee ; " George John- 

 son the " British Zoophytes ; " and Dr. Bowerbank the 

 " British Spongiidee." The microscope has its place 

 in the educational movement of the age, and it is the 

 more incumbent on opticians to manufacture an econo- 

 mic form of instrument, adapted to the wants of a large 

 and increasing class. In the selection of an instrument, 

 it must be borne in mind that a firm stand and a well 

 corrected object-glass are indispensably necessary. It 

 may be of some advantage to those who are about 

 to purchase an instrument if I were to shortly de- 

 scribe its several parts the stand, body, stage, sub- 

 stage, mirror, eye-piece and objective, seriatim. The 

 etand, the bearings upon which the superstructure of 

 the microscope rests, should be solid; and the foot 



