FIL 



FIL 



precision. The coarsest files have about 

 ten or twelve cuts in the inch of length, 

 and the very finest have upwards of two 

 hundred. 



As soon as the whole surface of the 

 file has been thus cut, the workman files 

 the bur off with a smooth file, so as to 

 leave very little more of the stroke than 

 what has entered below the original sur- 

 face ; and then proceeds to give the se- 

 cond or cross cut, forming an angle of 

 about sixty degrees with the finest range 

 of strokes. The intention to be answer- 

 ed by filing off the first edges is, to af- 

 ford a more even surface for cutting the 

 second, which is done exactly in the 

 same manner as the first range, and like- 

 wise to give a suitable figure to the small 

 teeth or lozenge-shaped prominences, 

 which stand up upon the face of the 

 file after the cutting is completed. If 

 this filing off were to be omitted, the 

 teeth would be pointed and irregular; 

 whereas the useful and durable "figure 

 is that of a small rounded chisel or 

 gouge. 



It may be remarked, upon examining a 

 file, that the first cut is always made more 

 slantwise than the second. If this were 

 riot done, the small teeth would all lie 

 behind one another, in rows in the direc- 

 tion of the length of the file, which would 

 make corresponding grooves in the face 

 of any piece of work that might be to be 

 filed, instead of leaving the workman at 

 liberty to vary his strokes, as is necessary 

 when a flat surface is to be produced. 



"When the file is cut and finished on 

 both sides, and on one or both edges, as 

 may be required, it is ready for harden- 

 ing, which is a chemical operation of 

 some skill and ingenuity. The heat is 

 given in a furnace, where the work can 

 be regularly disposed, and for fine work 

 a muffle is used. The file is first exposed 

 to a low degree of ignition, which burns 

 off any greasy or other matter that might 

 adhere to its surface. It is then dipped, 

 cold, in the grounds or thick sediment of 

 beer, and while wet, into a powder made 

 of burned or parched horn, or leather, or 

 other coally animal matter, and of com- 

 mon salt, and in this state speedily dried 

 by exposure to heat. Any other muci- 

 lage, which could be afforded at a mode- 

 rale price, would probably answer the 

 same purpose as the beer grounds. The 

 file being then put into the ignited muffle, 

 smokes, and soon becomes red hot, being 

 not only defended from oxydation, by the 

 covering of fused salt and animal coal 

 which envelopes it on all sides, but be- 



ing even rendered more steely upon its 

 sin-face by the absorption of cavbon. As 

 soon as it has acquired the low red heat 

 called cherry -red, it is taken out and 

 plunged into pure cold water, which in- 

 stantly cools it, and renders it very hard. 



There are several variations adopted 

 in the hardening process by different 

 workmen, by means of which they differ 

 in their success. Some file-makers, as 

 well as gunsmiths and locksmiths, pro- 

 duce the intended effect so completely, 

 that the whole surface of their work has 

 a beautiful dull-grey aspect, every where 

 alike ; whereas other operators produce 

 coully spots, which are obliged to be 

 cleaned off. The files, when quite dry 

 and clean, are slightly oiled, and kept in. 

 oiled paper. 



The simple operation of file-cutting 

 seems to be of such easy performance, 

 that it is not at all to be wondered at, that 

 machines for this purpose should have 

 been very early invented. Mathurin, 

 Jousse, in "La Fidelle Overture de 1'Art 

 de Serrurier," published at La Fleche, in 

 Anjou, in 1627, gives a drawing and de- 

 scription of one, in which the file is drawn 

 along by shifts by wheel-work, and the 

 blow is given by a hammer, which is 

 tripped by the machinery. There are 

 several in the *' Machines Approuvees 

 par 1' Academic Royale de Paris ;" and 

 one in the " American Transactions ;" 

 and a patent was granted a few years ago, 

 for improvements in the art, to the editor 

 of this work. 



The principal requisites in a machine 

 for file-cutting are, that the file should 

 be steadily supported, and the chisel 

 adapted to the face, without any unequal 

 bearing. Files are, however, for the 

 most part, cut by hand ; and the chief 

 reasons are, 1. The cut by hand is, from 

 its very nature, exactly of the depth the 

 bur demands; whereas, in a machine, if 

 the stroke be not nicely adapted to the 

 shift, the file may be either shallow cut, 

 or its bur may be thrown too close by an 

 over heavy stroke ; and 2. In machine cut 

 files, there must always be a piece left at 

 the beginning, at each corner, which re- 

 quires to be cut off before hardening. 

 This may be remedied in the machinery, 

 but it has not yet been done. 



FIL1CES, ferns, one of the seven fami- 

 lies or natural tribes into which the whole 

 vegetable kingdom is divided by Lin- 

 naeus, in his " Philosophia Botanica.'* 

 They are defined to be plants which bear 

 their flower and fruit on the back of the 

 leaf or stalk, which, in this class of 5m* 



