. The half-tone process. A practical manual of photo-engraving in half-tone on zinc, copper, and brass. Fig. 87. 154 THE HALF-TONE PROCESS. brass strip in which the plate is held, it is obvious thatthe T square must rule parallel lines at top and bottomand each side of the picture, forming perfectly right-angled corners, without the necessity of measuring ortrying with a set square. If the ruling board is not used, a right-angled steelset square, L shape, with both sides of equal thickness,is used, one line being struck and the others succes-sively ruled from it. Set squares of 450 of steel,eb
. The half-tone process. A practical manual of photo-engraving in half-tone on zinc, copper, and brass. Fig. 87. 154 THE HALF-TONE PROCESS. brass strip in which the plate is held, it is obvious thatthe T square must rule parallel lines at top and bottomand each side of the picture, forming perfectly right-angled corners, without the necessity of measuring ortrying with a set square. If the ruling board is not used, a right-angled steelset square, L shape, with both sides of equal thickness,is used, one line being struck and the others succes-sively ruled from it. Set squares of 450 of steel,ebonite, or transparent celluloid are also used for thepurpose. For ruling circles or elliptical border lines, either. big. 88. brass shapes are used as guides for the ruling pen, oran elliptograph (fig. 88) is employed. The latter is ahighly ingenious and useful little machine, which willrule any size of circle or oval most perfectly. It isprovided with a ruling pen for ink, and a graver to cutwhite lines. Most of the large photo-engraving houseshave these machines, which soon repay their cost wherethere is any considerable amount of work. To ensure neatness in lettering the name, line gauges THE ETCHING ROOM. 155 are used. These are small blades of steel, somethinglike a short length of watch spring, notched at the endto form two or three points, as the case may require,and these blades are set in brass holders about thelength and thickness of a retouching brush. When these gauges are run along a straight edge they make two or three fine parallel scratches on the surface ruledupon. Lettering drawn upon these lines can be madewith the letters of even height. A three-line gauge isused for capitals and
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Keywords: ., bookcentury1900, bookdecade1900, bookidhalftoneproc, bookyear1904
