studies, I shall be happy to resolve it if I can; and they may communicate
with me upon any such point without hesitation, in whatever quarter of the
world they may happen to be.


JOHN BOURNE.
9 BILLITER STREET,
LONDON,

_March 1st, 1856_.




PREFACE

TO THE FIFTH EDITION.

The last edition of the present work, consisting of 3,500 copies, having
been all sold off in about ten months, I now issue another edition, the
demand for the work being still unabated. It affords, certainly, some
presumption that a work in some measure supplies an ascertained want, when,
though addressing only a limited circle--discoursing only of technical
questions, and without any accident to stimulate it into notoriety,--it
attains so large a circulation as the present work has reached. Besides
being reprinted in America, it has been translated into German, French,
Dutch, and I believe, into some other languages, so that there is, perhaps,
not too much vanity in the inference that it has been found serviceable to
those perusing it. I can with truth say, that the hope of rendering some
service to mankind, in my day and generation, has been my chief inducement