The qualities requisite to a good shears for cutting metals are that the power required to do the work shall be distributed equally throughout the stroke; that the rate of cutting shall be uniform throughout the stroke; that the piece to be cut shall be held firmly in such a m'anner that all wrinkles or lends shall be removed from the part to be cut; that the edges of the blades shall pass each other at an equal distance throughout the stroke, and as near to each other as possible without mutual abrasion; and that the parts of the machine shall be so proportioned and adjusted as not to spring or to give any approximation to a drawing stroke in the blades. These, with the minor details of adjustment for different kinds of work, constitute the essentials of a good shears. The principle of action in the shears and the punch is identical. The punch is only a modification of the shears. The points above enumerated are not always easy to secure by simple means, where the blades of a shears are required to be of great length. As near an approach to ?.heir perfect attainment as we have ever met with has been secured in the invention we herewith illustrate. Having personally witnessed its operation we are prepared to testify to the very superior characterof the work it performs. Born of a necessity this invention admir-ably illustrates the old adago. The firm of Nichol Biller-well, of New York. city, manufacturers of ironworkiron shutters and other architectural workhaving taken a heavy contract at rates which subsequent circumstances threatened to make ruinously losing, the senior partner, Mr. Nichol, set himself to work like an able general, to turn defeat into victory. The result was the invention of this shears, the use of which enabled the firm to save themselves a large loss, and to realize a fair profit instead. In the engraving, A represents the framework of wood upon which the machine rests, B the movable cutter-bar, and C the clamp which holds the work. The movable cutter-bar is worked with a lever, D, so connected with the cutter-bsr by pivoted bars, that as the leverage of the shear blade is diminished, during the progress of the stroke, the leverage of D is increased to compensate for the loss, thus rendering the power required to work the shears uniform throughout the stroke. The clamp, C, consists of a straight square bar held by set-screws and attached by them to an angular casting, the cross section of which would be shaped like the letter L inverted. This casting extends over the whole 1 ength of the square bar, and with it forms the body of the clamp, the set screws passing at equal intervals through it, serving to adjust the clamp for different thicknesses. This clamp is worked by a lever, E, so arranged that the clamp is thrown uniformly down upon the work, or rather falls by its own weight by raising the lever. To the lever is attached an arm which, when the lever is depressed, raises the clamp and holds it during the adjustment ot the work. A metallic rack, P, seryes to hold the plate to bo cut, which is slid in to meet a system of gages not shown in the engraving. To the back side of the cutter bar, B, are bolted arms, G, which have friction rollers at the ends remote from the cutter bar, rolling against the back of the plates, I, attached to the standards, H. The plates, I, are slotted to admit the motionof the arms, G-, and are adjusted by set screws so that the edges of the shear blades can be brought and held closely together. This arrangement also prevents any lateral spring. In order to secure a uniform rate of cutting, the movable blade has a curved or bellying edge, so calculated that the latter end of the stroke cuts no faster than the first. The cutter bar, B, is raised by a chain and weight running over pulleys, as shown in the engraving. There is little doubt that for cutting sheets this shears is not excelled. It cuts perfectly clean, and leaves no burr. Be- fore its use in the establishment of Messrs. Nichol Biller-well, all the slats cut by them needed to have the edges dressed by the file. Slats cut by these shears are not touched with the file at all. Sheets of metal ten feet in length may be placed in these shears, and a mere shaving of uniform thickness and perfectly unbroken, taken from the edge the entire length, and what is still more astonishing, such a cut a mere threadis not curled or twisted. This could never j be accomplished by a shears having any lateral spring to the blade. The cut is made for the ten feet as rapidly as it could be done for ten inches. When working the average number of cuts made per day is 2,400, requiring a force of two ordinary laborers and two boys. It is perfectly easy to apply steam or water power to the operation of this shears by means that will suggest themselves to any mechanic. We are informed by the inventor that its use saves half the labor of any other machine now in use for cutting iron, a result which we can readily credit, having seen the machine at work, and noted the excellent characterof the work performed. The patentee will sell rights for all States except New York. The patent for this invention was obtained through the office I of the Scientific American Patent Agency, May 18, 1869, by I John Nichol ot the above-named firm. The machine may be seen in operation at the works of Nichol Billerwell, 220, 223, and 224 West Houston street, New York, to whom all communications may "be addressed, A NEW illuminating- mixture consists of two parts rape-seed oil and one of petroleum oil.