. The half-tone process. A practical manual of photo-engraving in half-tone on zinc, copper, and brass. Fig. 85. Fig. 86. convenient to have the magnifiers supported on a standwith swinging telescopic arr, as fig. 84. When working by artificial light, a bulls-eye lens, or a water - globe lens ( and 86), must be pro-vided to focus the light ofthe lamp on to the plate. The ruling of borderines, and the writing orengraving of the imprintname in the corner of theplate, are usually done onthe fine etchers useful appliance for aiding the ruling of the borderlines is the ruling board (
. The half-tone process. A practical manual of photo-engraving in half-tone on zinc, copper, and brass. Fig. 85. Fig. 86. convenient to have the magnifiers supported on a standwith swinging telescopic arr, as fig. 84. When working by artificial light, a bulls-eye lens, or a water - globe lens ( and 86), must be pro-vided to focus the light ofthe lamp on to the plate. The ruling of borderines, and the writing orengraving of the imprintname in the corner of theplate, are usually done onthe fine etchers useful appliance for aiding the ruling of the borderlines is the ruling board (fig. 87). This is a well-clamped board with a slot runningdiagonally across it, and a raised strip of brass on twosides of the board, thusforming a right angle, inwhich the plate lies andis held by a clamp whichruns in the diagonal T square with an ad-justable head is used inconnection with thisboard. If the picture isnot quite parallel on theplate the T square is set to any perpendicularobject. The head of the square being screwed upand pushed against the outside edge of the right angle. 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
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Keywords: ., bookcentury1900, bookdecade1900, bookidhalftoneproc, bookyear1904
