3viv PREFACE. 



veau, when reforming the nomenclature of Chemistry, the sound- 

 ness of which Dugahl Stewart has recognised : — " Nefaites grace 

 aaucune denomination impropre. Ceux qui saventdeja, entendront 

 toujours ; ceux qui ne savent pas encore, entendront plutbtr 



Throughout the whole publication, wherever any fact of import- 

 ance not depending on their own authority is mentioned, a refer- 

 ence to the source whence it has been derived is generally given ; 

 so that, if the work should have no other value, it will possess that 

 of saving much trouble to future inquirers, by serving as an index 

 to direct them in their researches. 



The Authors are perfectly sensible that, notwithstanding all 

 their care and pains, many imperfections will unavoidably remain 

 in their work. There is no science to which the adage, Dies diem 

 docet, is more strikingly applicable than to Natural History. New 

 discoveries ai*e daily made, and will be made, it is probable, to the 

 end of time ; so that whoever flatters himself that he can produce 

 a perfect work in this department, will be miserably disappointed. 

 The utmost that can reasonably be expected from naturalists, is to 

 keep pace with the progress of knowledge ; and this the authors 

 have used their best diligence to accomplish. Every new year since 

 they took the subject in hand, up to the very time when the first 

 sheets were sent to the press, numerous corrections and alterations 

 have suggested themselves ; and thus they are persuaded it would 

 be were they to double the period of delay prescribed by Horace. 

 But Poetry and Natural History are on a difierent footing ; and 

 though an author can plead little excuse for giving his verses to 

 the world while he sees it possible to polish them to higher excel- 

 lence, the naturalist, if he wishes to promote the extension of his 

 science, must be content to submit his performances to the public 

 disfio'ured by numerous imperfections. 



In the introductory letter several of the advantages to be de- 

 rived from the study of Entomology are pointed out ; but there is 

 one which, though it could not well have been insisted upon in 

 that place, is too important to be passed over without notice, — its 

 value in the education of youth. 



All modern writers on this momentous subject unite in re- 

 commending in this view Natural History ; and if " the quality 

 of accurate discrimination, the ready perceptiwi of resemblances 



