All these tools are either manufactured by the Messrs. Leonard themselves at the “Matteawan works,” employing some three hundred and fifty hands, or furnished from the “Lowell machine shops,” where from five hundred to a thousand hands are constantly employed in this class of business; or, again, from “The Great Hadley-Falls shop,” at Holyoke; all of which establishments are represented by the same firm, and all of which turn out work, which--it is believed--cannot be surpassed, if equalled, in the world. The first of these machines which we propose to notice, a representation of which stands at the head of this paper, is perhaps one of the most important, if not the most important of all the tools employed in the machine shop. This engine has already been noticed in Graham, as employed in the noble press-works of Messrs. Hoe & Co., of New York--vol. XL., No. 6, p. 576. It is used for finishing the surfaces of whatever portions of the machinery must be brought to a smooth and polished face. This is done by the propulsion of the pieces of iron to be planed in a horizontal and longitudinal direction against cutting edges, which again move horizontally across the moving planes, and are pressed downward on them vertically, so as to effect the planing to the uniform depth required. The abraded portions of the metal are thrown off--from the surface of cast iron in a sort of scaly dust, from that of wrought iron in long curled shavings--and the planes can be wrought up to almost any desirable degree of smoothness and finish. It is but a short time, comparatively, since this machine was first introduced: it is one of the most important among mechanical tools; and it is indeed a triumph of art to see one of these machines under the direction of one person, performing the usual labor of some fifteen or twenty mechanics in former times with their chisels and files. Art observes, and experience confirms the fact, that machinery can and does perform work much more accurately than the most skillful mechanic; and, perhaps, in no instance is this general principle so happily illustrated as in the performance of these machines. The usual cost of motive power is about twenty-five cents per day, per horse power, and allowing one horse to be equivalent to five men, we shall have the labor of one mechanic furnished for five cents a-day. From this it will be seen how important every invention or improvement becomes to the machine-builder, which tends to perform the usual labor on the machine by machinery. The above cut represents a very excellent planer. There is a great degree of taste and finish employed in its design; indeed the builder may flatter himself that he has one of the best machines built in this country.