facts which thus came under my attention, as well as of the
reflections which they suggested, induced me to believe that the
publication of some of them might be of use to persons who
propose to bestow their attention on those enquiries which I have
only incidentally considered.  With this view it was my intention
to have delivered the present work in the form of a course of
lectures at Cambridge; an intention which I was subsequently
induced to alter.  The substance of a considerable portion of it
has, however, appeared among the preliminary chapters of the
mechanical part of the Encyclopedia Metropolitana. 

I have not attempted to offer a complete enumeration of all
the mechanical principles which regulate the application of
machinery to arts and manufactures, but I have endeavoured to
present to the reader those which struck me as the most
important, either for understanding the actions of machines, or
for enabling the memory to classify and arrange the facts
connected with their employment.  Still less have I attempted to
examine all the difficult questions of political economy which
are intimately connected with such enquiries.  It was impossible