From this they are distributed to the different processes in order--the first of which is cutting the teeth. Certain classes of horn-plates, however, are subjected to a farther process of planing on the surface preliminary to this operation; but in all plates which have been hot-pressed, and are intended to be stained, this is unnecessary, and therefore they are taken when perfectly dry to the cutting department. On entering this department the visitor is sometimes bewildered. The incessant and peculiar clatter of the machinery, the heat of the place, and apparent confusion, produce together a curious effect. A little observation, however, shows that we have arrived at the basis of all the modern improvements in comb-making. On benches around the apartment, in close proximity to each other, were twenty-four "twinning-machines"--the invention, with its subsequent improvements, to which we have referred. Each of these is worked by a man, with an attendant who keeps up a supply of hot plates from the fires arranged for that purpose in the centre of the room. It is impossible without diagrams to explain the principles and construction of this apparatus; but there can be no mistaking its effect. A plate of horn, after being heated, is placed on a small carriage within the cast-iron frame of the machine, which travels by means of a particular arrangement of gearing on parallel slides. Immediately over this are two angular-shaped chisel-like cutters, which, on the application of motive power, descend on the horn with an alternating motion, and an inconceivable degree of rapidity and force. Before we could well see, far less understand, the rationale of the process, we were shown the horn cut in two pieces--_one half literally taken out of the other_, and each presenting the well-defined outline of a comb. In this cutting department resides the perfection of that beautiful mechanism that revolutionized the trade and reduced it to mathematical precision. To appreciate this we have only to look at the increase it has effected in the production. A comb-maker of the old school could not perhaps, with all his skill, cut more than eighty or a hundred combs per day; while with this machinery a man and boy will cut upwards of _two thousand_ of the same kind, and with a consumption of only half the material. The finer dressing-combs, and all small-tooth combs, are still cut by circular saws in the next department. Here, however, a moderately curious visitor will not linger. A dense atmosphere of horn dust fills the large apartment, and gives to every thing within its influence the white appearance that distinguishes a flour-mill, to which indeed at first sight it bears a striking resemblance. From the notes we took, we learn that here there are wheels on the fine self-acting machinery, in connection with the cutting and pointing of combs, that revolve 5000 times in a minute, and saws so delicately fine as to cut forty teeth within the space of an inch.