IN submitting the second volume of the work on Turning and Mechanical Manipulation to public scrutiny, two subjects call for the Author's especial notice; the delay in its appearance, and the reason for the proposed augmentation of the number of the volumes, intended to constitute the work, from five to six.

The delay has been caused principally by the unexpected manner in which the subject matter of this volume has been extended by additional examples and illustrations - also by great and unavoidable interruptions caused by the Author's general engagements - and by some domestic calamities, the most severe of which has been the loss of the Author's eldest son.

The division of the matter that was originally meant to compose the second volume, has been mainly caused by a desire to lessen the disappointment, which has been repeatedly expressed the delay in the progress of the work. This division, although it has increased the number of the volumes from five to six, has not caused any further departure from the original scheme of the work, as will be seen on the perusal of the titles of the distinct treatises of which it is proposed to consist.

A few unimportant errors in the references to the several volumes, will naturally ensue from this augmentation in their number, but as the references to the pages, to the woodcuts, and to the appendix notes, will be consecutive throughout the three preliminary volumes, it is hoped that no confusion will be experienced in consequence.

In conclusion the Author has to repeat his former request that any omissions, errors, or ambiguities may be pointed out for correction in the subsequent appendixes; and as he has bestowed an equal amount of care on the production of this, as on the first volume, a second edition of which is also this day published, the Author hopes to be again rewarded with some measure of public approval. He promises to use his best exertions in the furtherance of the work, and as some of the matter is in preparation, and none of the remaining volumes are expected to exceed the first in extent, he hopes not to be again compelled to trespass so long on the patience of his readers.

Charing Cross, Lowdow,

November 10, 1846.