among mechanics, a tool used in metal, &c., in order to smooth, polish, or cut.

This instrument is of iron or forged steel, cut in little furrows, with chisels and a mallet, this and that way, and of this or that depth, according to the grain or touch required. After cutting the file, it must be tempered with a composition of chimney foot, very hard and dry, diluted and wrought upon with urine, vinegar, and salt, the whole being reduced to the consistence of mustard. Tempering the files consists in rubbing them over with this composition, and covering them in loam; after which they are put in a charcoal fire, and taken out by that time they have acquired a cherry colour, which is known by a small rod of the same steel put along with them. Being taken out of the fire, they are thrown into cold spring water; and, when cold, they are cleaned with charcoal and a rag; and being clean and dry, are kept from rust by laying them up in wheat bran. Iron files require more heating than steel ones. Files are of different forms, sizes, cuts, and degrees of fineness, according to the different uses and occasions for which they are made. See Filing.

the art of war, a row of soldiers, standing one behind another, which is the depth of the battalion or squadron. The files of a battalion of foot are generally three deep; as are sometimes those of a squadron of horse. The files must be straight and parallel one to another.

Law, a thread, string, or wire, upon which writs and other exhibits in courts and offices are fastened or filed, for the more safe keeping, and ready turning to the same. A file is a record of the court; and the filing of a process of a court makes it a record of it. An original writ may be filed after judgment given in the cause, issued forth before; declarations, &c., are to be filed, and affidavits must be filed, some before they are read in court, and some presently when read in court. Before filing a record removed by certiorari, the justices of B. R. may refuse to receive it, if it appears to be for delay, &c.; and remand it back for the expedition of justice: but if the certiorari be once filed, the proceedings below cannot be revived. An indictment, &c., cannot be amended after it is filed.