and the Economy of Fuel. 29 



paying so little attention to method in this Essay, as to 

 postpone so long the investigation of the elementary 

 principles of the science I have undertaken to treat. It 

 may be thought that the part of the subject I am now 

 about to consider should have preceded all other inves- 

 tigation ; that instead of occupying the middle of my 

 book, it ought to have been discussed in the Introduc- 

 tion, or at least to have been treated in the beginning 

 of the first chapter. But if I have been guilty of a 

 fault in the arrangement of my subject, it has arisen not 

 from inattention, but from an error of judgment. De- 

 sirous rather of writing a useful book, than of being 

 the author of a splendid performance, I have not scru- 

 pled to transgress the established rules of elegant com- 

 position in all cases where I thought it would contribute 

 to my main design, public utility ; and well aware that 

 my book, in order to its being really useful, must be 

 read by many who have neither time nor patience to 

 labour through an elementary treatise upon so abstruse 

 a subject, I have endeavoured to decoy my reader into the 

 situation in which I wish him to be placed, in order to 

 his having a complete view of the prospect I have pre- 

 pared for him, rather than to force him into it. If I 

 have used art in doing this, he must forgive me; my 

 design was not only innocent, but such as ought to 

 entitle me to his thanks and to his esteem. I wished 

 to entice him on as far as possible, without letting him 

 perceive the difficulties of the road ; and now that we 

 have come on together so far, and are so near our jour- 

 ney's end, I hope and trust that he will not leave me. 

 To proceed, therefore 



