FILE. 605 FILEFISH. ing reversed during the operation < ij cutting as necessitj requires. Tlie usual different sectional shapes of com- mercial tiles are shown in the accompanying illus- tration. In length such riles range from three inches to twentj inches. Smaller tiles for je ers, die-sinkers, and watchmakers, and i die lUis arc made of Bpecial mate rial, and in variou special sizes. As indicating the small sizes in which files are produced, it maj be noted that the* smallest size of Nicholson round broach file is but .033 of an inch in diameter, and about ra ih long- Majttjfactube. Formerly, all files were hand- made, the steel bar being forged to shape, ground smooth, and crft hy hand tools. Most tiles are now made by machinery designed to perform all of these essential operations. '1 lie old method of hand cutting has a peculiar interest because of the deftness and skill required of the workman, and it will be described briefly for this reason, and also because it will help to explain the na- ture of the work required of modern file-cutting machinery. The following description is taken from Holzapffel's Turning and Mechanical Ma- nipulation : "The first cut is made at the point of the file ; the chisel is held in the hand at a horizontal angle of about 55° with the central line of the file, and with a vertical inclination of about 12° to 14° from the perpendicular. . . . The blow of the hammer upon the chisel causes the latter to indent and slightly to drive forward the steel, thereby throwing up a trifling ridge or bur: the chisel is immediately replaced on the blank and slid from the operator, until it encounters the ridge previously thrown up, which arrests the chisel or prevents it from slipping farther back, and thereby determines the succeeding position of the chisel. The heavier the blow, the greater the ridge, and the greater the distance from the pre- ceding cut at which the chisel is arrested. The chisel, having been placed in its second position, is again struck with the hammer, which is made to give the blows as nearly as possible of uni- form strength; and the process is repeated with considerable rapidity and regularity, 00 to 80 cuts being made in one minute, until the entire length of the file has been cut with inclined, parallel, and equidistant ridges, which are col- lectively denominated the first course. So far as this one face is concerned, the file, if intended to be single cut, would be then ready for hardening. Most files, however, are double cut: that is, they have two series or courses of chisel cuts. In cutting the second course, the chisel is inclined vertically as before, at about 12°, but its edge only a few degrees from the transverse line of the file, or about 5° to 10° from the rectangle. The blows are now given a little less strongly, so as barely to penetrate to the bottom of the first cuts, and from the blows being lighter they throw up smaller burs, consequently the second course of cuts is somewhat finer than the first. The two series, or courses, fiil the surface of the file with teeth, which are inclined toward the point of the file." At first sight it would appear from the sim- plicity and continual repetition of the movements required in file-cutting that it was an operation especially adapted to be performed by machinery. Nevertheless, it was not until many years after the first inventor of a file-cutting machine had i hi- dr ice thai file cut! ing machines were >•■ ised, and i hat machine cut tiles could compete with the hand made product in the mat i.ci . Among t he di tab ile cul • ting machine-, maj be mentioned Du i 1699) ; Fardonet I 1725) ; Thioul - chal and Gamin ■ 1765 Ts | ; Raou] i I i ii and Winton (1847). None of ihe-e machines was com- mercial; ful. In 1865, however, Mr. V. T. NKcholson oi Providence, R. I., in- rented a file cut i in" machine, which, as improved and lifted from I ime to I ime, is now ■ te I; u ed in I he Unit N i > • ■ > 1 1 the ami ti M. Bernot, a French- man, devised a machine which proved me: cia llj ucce ful. Briefly described, t hi cessful form-, of file-cutting machines consist of a moving fable on which i L. id, blank is fixed, and which moves it progressively tmdei of trip-hammer arrangement carrying cutting chisels. In making machine-made files the bars of steel are first forged by hand or by ma< and then ground smooth. The smoothed blank is then run through the cutting machine. The final process is to temper and harden the cut file. Filing. To the uninitiated thi ma eem a simple operation of rubbing one piece of metal upon another, requiring only musculai tt and no skill. This is far from being thi for a skillful workman will in a given time, with a given amount, of muscular i away a far greater quantity of metal with a fill than one who is unskillful, for he makes tooth cut Into the work, instead of mi, hum ovei it. To do this, he must adapt the pressun and velocity of motion of the file to the coarseness of its teeth, and the hardness, brittleness, and toughness of the material he is winking upon. To file lint — that is, to avoid rounding the sharp I I a narrow piece of work — i- very difficult, and some years of continual practice is required before an apprentice can do this well, especially in 'smoothing up' or finishing work before polish- ing, and there are some who never succeed in filing, smoothing, and polishing without rounding the edges of fine work. The power of doing Ibis constitutes the main test of skill among niathe- inal ieal -instrument makers and other metal work- ers. The flattest surface can be obtained by lay- ing the work, where its form admits, upon of cork held in the vise, and filing it with one hand; the pressure on the file being communi- cated by the forefinger. It is mainly to aid workman in filing flat that the rounded or bellied form is given to files: this partially compensates the tendency of the hands to nun.- in a curved line with its convexity upward when the move forward, and apply pressure, as in the act of filing. FILEFISH. One of a family (Mot thidse) of small tropical and semi-tropical fishes closely related to the plectognath trigger-fishes (q.v.). The scales are very small and rough, giv- ing the skin a velvety appearance, and making it able as a polishing material. The name refers to the file like appearance of the stout dor sal spine, which is rough, and armed behind with ps of barbs. The type genus, Monacanthus, contains several species, but the best known file- lisb is the 'barnacle-eater' (Alutera Schcepffi), which ranges northward to New England, maj I" 18 inches long, and has a "bright skin, sometimes
