The ducking stool is mentioned in the Doomsday survey; it was extensively in use throughout the country from the fifteenth till the beginning of the eighteenth century, and in one rare case at least—at Leominster—was used as lately as 1809.
The Story in Photo-Engraving[30]
Modern advertising would not have been possible without photo-engraving. Attention has been attracted, desire has been created and goods have been sold, largely through the pictorial or other artistic embellishments which have lifted particular “ads” out of the mass and attracted the favorable attention of the cursory reader. Pictures are the universal language, not only to those of divers tongues, but to those of every stage of mental development.
Photo-engravings are a comparatively modern product. They superseded wood engravings, which for years has been the recognized medium for illustrations to print on a type printing press. Photo-engravings, broadly speaking, are divided into two classes—line engravings and halftones. The distinction between them lying in the fact that one, as its name implies, is a reproduction of a drawing made in lines or stipples, while the other, the halftone, gets its name from the method of its manufacture.
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.
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.