VI PREFACE. 



Should the work achieve this, and contribute also to greater 

 precision than has hitherto been attained in the arrangements, 

 structures, and estimates required for works of public or private 

 utility, one of the objects for which it was originally undertaken 

 will be crowned with success. 



In the spring of 1838, Gcov fleXovroc, another volume of 

 Mechanics of Fluids will appear, comprising Hydraulics, which, 

 as the term implies, will exhibit the principles of Dynamics in 

 the joint operation of air and water, hydraulic architecture, and 

 the principles of construction of various machines and engines 

 which belong to the mechanics of fluids. 



In conclusion, we vir tvK\tiq 0avw, I beg leave to observe, 

 that as my own avocations did not allow me sufficient leisure 

 to complete such an undertaking as these volumes are, in any 

 reasonable time, I have availed myself of the services of 

 WM. TURNBULL, the author of a treatise on Cast-iron Beams 

 and Columns ; and it affords me unfeigned satisfaction to ac- 

 knowledge the extent of his abilities and the accuracy of his 

 calculations, in subjects connected with the mechanics of fluids. 



Quam, sit uterque, libens (censebo) exerceat artem. 



But having elsewhere alluded to the calculations and exam- 

 ples which abound in this volume, I shall only here remark, 

 that, were it necessary to plead authority for such exercises, 

 I might quote NEWTON himself, who has thus recorded his 

 opinion : " In scientiis ediscendis, prosunt exempla magis quam 

 prtecepta." '' . r ' 



The wood-engravings, so well executed by Mr. G. VASEY, 

 are sufficiently intelligible, and possess besides the lasting 

 property of being destroyed only with the page in which they 

 appear. 



A. J. 



Wyke House , Sion Hill, 

 Isleworth, Oct. 19, 1837. 



