The author was led to undertake the present work on Turning and Mechanical Manipulation, from the circumstance of there bring no general treatise in the English language for the guidance of the Amateur in these pursuits. The original works by Plumier and Bergeron, although they were suited to the periods at which they were produced, are neither of them sufficient to convey instruction adequate to the present state of the Art; and the more recent French works leave unnoticed a large portion of the machines and instruments now used by Amateurs.

The greatest difficulty the author has encountered in his task, has been that of selection and arrangement; so as to produce, from materials so numerous and dissimilar, a work of general reference and practical instruction, at once sufficiently copious and accessible. But he hopes this difficulty has been satisfactorily met, by the division of the work into five volumes, upon parts of the subject which are broadly distinguished,and which thereby renders the volumes in a great measure independent of each other. This plan is also carried out in the subdivision of the volumes into chapters, which may be considered severally to include all that was deemed necessary to be stated upon the respective subjects; or to be, so far as they extend, distinct treatises; and which, in cases of doubt, he has not hesitated to submit to various practical friends for confirmation or extension.

These appeals have been answered with an alacrity which calls for his warmest thanks; and the author gladly avails himself of this opportunity of acknowledging these sendees, which have given a great additional value to his labours.

The work being of a technical nature, the author hopes to escape literary criticism, his main object having been to treat every subject in clear and concise language. As, however, notwithstanding his utmost care, he cannot expect to have been so fortunate as entirely to have escaped errors, ambiguities, or omissions, he requests of his readers the favour of the communication of any such defects, in order that those of most material import may be noticed in the Appendix to the second and ensuing volume, a great part of which is already completed.

CHARING CROSS,

January 1, 1843.