Briefly stated, the process of making halftones is as follows: The subject to be engraved is photographed through a halftone screen, so-called. This halftone screen is a glass plate ruled with lines at right angles ranging, for different purposes, from 60 to 200 lines to the inch. This screen is placed between the lens and the sensitized plate which is to be the negative. The necessity for this screen is due to the fact that a photograph is made up of “tones.” That is to say, that the color changes imperceptibly in subtle gradations of light and shade. If this copy were photographed on a piece of copper it would present no chance for the etching fluid to act. The idea is to break up the surface into various sized dots, as the various gradations of color on the original cannot be transferred by any other method to a sheet of copper and etched. [Illustration: HALFTONE ENGRAVING] The various tones must be changed either to lines or dots, so as to make a printing surface for the ink roller of the press to operate. This is necessary to get the desired printing surface. The dots are of various sizes, ranging from a minute stipple to a solid black, and they present to the eye the same effect as the unbroken tones of a photograph. The negative when finished shows the drawing exactly like the original. The whites are opaque, the solid blacks are clear glass, the intermediate tones showing the same values in stipples of various sizes. The film of the negative is next removed from the glass, turned and placed on a heavier plate glass with a number of others and printed on a sheet of metal which has been coated with a sensitized solution. This plate of heavy glass containing the several negatives is placed with the sensitized metal in a printing frame. The light passes through the clear part of the negative, the solid parts prevent the passage of light; thus we have the light acting chemically on the sensitized surface. After the print is removed from the printing frame, it is developed, the parts acted on by the light adhering to the metal. The opaque parts, through which no light has penetrated, leave the solution soft on the surface of the metal. This is removed by placing in water and wiping gently with absorbent cotton. The print is then dried and heated over a stove which bakes the sensitized solution to the metal. It can readily be seen that this sheet of metal is now in such shape that the etching fluid will etch away the uncovered portions of the metal and allow the protected parts, which represent the color of the original, to remain in relief. [Illustration: LINE ENGRAVING]