We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
96 THE ADVANCE OF PHOTOGRAPHY
Near the little Bavarian town of Solenhofen, there is a clayey, rather porous limestone, easily polished and worked. Such limestone is used for lithography.
The lithographic press differs essentially from copperprinting and book press, because the drawing on stone is neither raised nor incised. The lithographic stone forms, when ready for printing, a smooth surface ; and in this the process is peculiar, differing from all other modes of printing. If a drawing is made on a lithographic stone with ink consisting of colour and a fatty substance, e.g. oil, and the stone is moistened with water, the porous stone is wetted only in those places where there is no oily colour, for oil repels water. An oily ink, such as printer's ink, is then rubbed on the stone with a leathern roller and only adheres to the previously inked spots — that is, to the drawing.
This peculiarity was discovered by Alois Senefelder in 1796. He also turned his discovery to practical account, and applied for patent rights in England, Austria, and Germany during the years 1800-1803.
After the stone has been inked as above, if a piece of paper is pressed upon it the ink passes over to the paper, and a lithographic impression is obtained. The stone can be evidently used any number of times, and thus thousands of copies can be produced. This style of printing has many advantages over copper engraving. The engraving of a copper plate is a difficult matter, often requiring a labour of years, whereas the drawing on stone is almost as easily made as on paper. In like manner, printing from a stone plate has fewer difficulties than that from a copper plate. Corrections are easier to make on the stone, and further, after the surface has been removed by grinding, the same stone may be used for another drawing, and so on for many years. These circumstances have brought lithography into general use : technical drawings, labels, circulars, visiting cards, price lists, calendars, illustrations of books, atlases,