In offering to the public the third volume of the late Mr. Charles Holtzapffel's work on Turning and Mechanical Manipulation, some explanation is required of the circumstances under which the work has been continued. On the premature and lamented death of the highly talented author, it became necessary either to abandon the work, or to endeavour to realize the views with which it had been undertaken. In deciding on the latter course, Holtzapffel & Co. were influenced partly by the circumstance, mentioned in the preface to the first volume, of the absence of any general treatise in the English language for the guidance of amateurs of mechanical pursuits, but principally by the desire of fulfilling the intentions of the author, and of preventing disappointment to his kind and numerous patrons, who have most strenuously urged the importance of completing the work, more especially as the first two volumes had been so favourably received by the public.

The arrangement of the subjects to be treated on in the present and succeeding volumes had been determined on by the late author, many notes had been written, and considerable progress made in the advancement of the work. The third volume being now completed, it is respectfully submitted to the public, with humble confidence that it will be received with leniency.

In compiling the present volume every endeavour has been made to follow, as closely as possible, the course indicated by the late Mr. C. Holtzapffel, and it is trusted that these efforts have been in great measure successful; but notwithstanding that every care has been taken to render this part of the work as complete and correct as possible, imperfections, omissions, and errors, have doubtless arisen; it is hoped that these defects will be viewed with liberal kindness, and pointed out for future correction.

In conclusion, it may be permitted to mention that the delay in the completion of the present volume has been considerably increased by the interruptions of ordinary business, and other circumstances wholly unavoidable. It is, however, fully expected that the fourth volume will be published within a much more limited period, as the late author's notes on its subjects are more complete, and upwards of one hundred and fifty pages had been printed under his personal superintendence.

Charing Cross, London, December 5, 1850.

Errata

Page

1027, line 10 from bottom, for This, read Thus.

1067, line 12 from bottom, for Chap. XXXIII., Section 2, read Chap. XXXII

Section 3. 1078, line 11 from bottom, for Durbec, read Purbec. 1151, line 4 from top, for off, read of. 1224, line 1 at top, for leve, read level. 1368, line 14 from bottom, for soft iron, read soft iron wire.