Hfc 



PEEFACE TO THE THIRD AND 

 EDITIONS. 



Y endeavour to produce a cheap and 

 popular guide to the use of the Micro- 

 scope has been rewarded by a success 

 which has far exceeded my expecta- 

 tions. In a short space of time, three 

 editions, each of Jive thousand copies, have been 

 sold ; and I am now called upon for a Fourth. 



My efforts on this occasion have been directed 

 to a revision of the whole work ; much new matter, and a 

 large number of additional cuts to illustrate the text, have 

 been added ; and I trust I have succeeded in making the 

 present Edition more free from blemish and more generally 

 useful to the student and the public than those which pre- 

 ceded it. I have at all times freely and fully availed 

 myself of the judicious suggestions and criticisms of kind 

 friends ; and I wish to take this opportunity of acknow- 

 ledging the obligations I am under to those who have 

 so generously accorded to this small work, whatever its 

 defects, their meed of approbation. 



J. H. 



1859. 



S3S9403 



