PREFACE 



TO 



THE THIRD EDITION. 



It is a usual and indeed very naturally enter- 

 tained idea, that when any book has gone through 

 more than one edition, the work must comprise 

 some merit to render such repetition necessary or 

 advisable. 



Takino; this idea in its oreneral bearins; the 

 conclusion drawn is more or less a correct one : 

 yet it may lead to very erroneous judgment as to 

 the extent of the sale of any published work, so 

 far as relates to the numerical quantum of copies 

 sold ; for where a work is of such a nature that 

 the price of each volume is somewhat high, both 

 author and publisher may feel it prudent to con- 

 fine an edition to a few hundred copies : whereas, 

 on the other hand, where the price is very moderate, 

 it may be judicious, indeed necessary, to let the 

 edition comprise some thousands, in order to 

 render the work remunerative : thus one work 



A 2 



