Many contrivances have been devised for obviating this evil, but the fork-grinders have not seconded these efforts so zealously as might have been expected. In making pen and pocket-knives, a slender rod of steel is heated at the end, hammered to the form of a blade, and carried through many subsequent processes. But the putting together of these hinged knives requires more time than the making of the blades, and affords a curious example of minute detail. When the pieces of bone, ivory, pearl, tortoise-shell, horn, or other substances, which are to form the outer surface of the handle, are roughly cut to shape; when the blade has been forged and ground, and when the steel for the spring is procured, the whole are placed in the hand of a workman, who proceeds to build up a clasp-knife from the little fragments placed at his disposal. So many are the details to be attended to, that a common two-bladed knife has to pass through his hands seventy or eighty times before it is finished. A file, as every one knows, is a steel instrument, having flat or curved surfaces so notched or serrated as to produce a series of fine teeth or cutting edges, which are employed for the abrasion of metal, ivory, wood, &c. Steel for making files being required to be of unusual hardness, is more highly converted than for other purposes, and is sometimes said to be _double converted_. Small files are mostly made of cast steel. The very large files called _smiths’ rubbers_ are generally forged immediately from the converted bars. Smaller files are forged from bars which are wrought to the required form and size by the action of tilt-hammers, either from blistered bars or from ingots of cast steel. These bars are cut into pieces suitable for making one file each, which are heated in a forge-fire, and then wrought to the required shape on an anvil by two men, one of whom superintends the work while the other acts as general assistant. The next operation upon the blanks which are to be converted into files is that of _softening_ or _lightening_, to render the steel capable of being cut with the toothing instruments. This is effected by a gradual heating and a gradual cooling. The surface is then rendered smooth, either by filing or grinding. [Illustration: File Cutting. File Cutting.]