In introducing this treatise on wood machines to the public, the Writer asks for its charitable consideration; and while he has no apologies to make for attempting to furnish such a work, he has many to offer for the lack of positive data which would have added to its value. His experience is that of a constructor of machines rather than of a writer of books, and but for the circumstance that no other work of the kind has appeared, such a task would not have been assumed. To write of an art that has passed through the hands of the scientific and the learned is a “dangerous thing,” but when parallels and comparisons are wanting, and when there is a real and admitted need of such a treatise, it is comparatively safe. Shielding himself behind these conditions, the Writer would call attention to the fact that while every other branch of the industrial arts has been the subject of treatise upon treatise, scientific and practical, wood machines have never been considered. The importance of the woodworking interest, in England and America, gives it a rank that should have claimed at least some place in our voluminous text-books, but not a line appears in them relating to the subject, if we except a brief part of Prof. Rankine's late work on machine tools, Molesworth’s pamphlet on wood conversion, and Worssam on saws. Notwithstanding this, it is safe to assert that with their high speed and endless modification wood machines demand a higher grade of ingenuity and skill in their construction than machines for cutting and shaping metal. Accurate balancing, centrifugal force, the strength and arrangement of framing to resist vibration, and many other elements that belong to machine construction, have their greatest importance in wood tools. It is easy to calculate the strain and provide for the proper performance of cutting tools moving at sixteen feet a minute, but when these cutting edges are moved five to ten thousand feet in the same time, a new set of conditions are involved, conditions that cannot be predicated upon the ordinary laws of construction, but have, with our present knowledge of the art, to be founded solely upon experience and observation.

The want of that scientific consideration to which wood machinery is so fully entitled, must in a great measure account for the imperfect manner in which much of it is made. In many, if not in the majority of the shops in America, there is no system of drawings, no standard for bearings, bolts, or shafting ; the metal in the framing is disposed in the most unaccountable manner, in fact there is nothing approaching the standard of our machine tools, except the paint, which is laid on in "variegated profusion."

But it is outside the province of this work to criticize, inasmuch as it is not assumed to be a regular text-book. Yet it will not be amiss to “stir the matter up," and thus provoke the attention which the importance of this great interest demands.

As it was stated in the outset that no apology was needed for the introduction of this work, it is superfluous, for the same reasons, to apologize for its not being a text-book, - there is nothing to form a text-book from. The limited experience of one person can furnish but little material for such a work. If it is desired to prepare a treatise on the steam-engine or machine tools, or in fact on any of the common branches of mechanism, except wood machines, you have only to go to any scientific library, and the whole thing is before you, - rules, formulae, drawings, repeated by a score of writers; but to write of wood machines there are no such data. Let this be a sufficient apology for what this treatise may lack, as compared with treatises devoted to other branches of engineering.

The plan adopted is to notice in a general way the several leading operations in wood conversion, with the construction and operation of the machines in modern use, introducing such rules, and treating of such laws as have been fixed by practice and experience, and have come within the knowledge of the Writer during an extended experience in designing and constructing both standard and special machines for wood work. It is to be regretted that during this experience, which was at all times divided with the charge of extensive manufacturing interests, no notes or memoranda were taken, as these would have been of invaluable assistance in the preparation of this treatise.

Special machines and adaptations, from the limits of the work, receive but little notice. Their consideration, to have any value, would require facts and statistics which, with the drawings needed to explain them, would have carried the extent of the treatise far beyond its plan.

It is, however, intended, if future interest seems to warrant it, to prepare a supplementary treatise on special machines for wood conversion, which shall include all of interest that is omitted here.

With these explanations, the work is submitted to the makers and users of wood-cutting machines, many of whom the Writer has the honour of knowing personally.