OFFSET AND OFFSET MACHINERY : By DANIEL T. POWELL MONG modern methods of printing is that known as " Off- set," and very special machinery has been designed by several printing-machine manufacturers which produces rather start- ling results. The Word offset is merely the reversal of the two-syllable word " set-off," a word execrated in every printing ofiice by every machine printer. Yet one may, looking back on the years of long ago, readily reason out how " set-off " has been turned to good account for the printer in " offset." Who being a letterpress printer, the origin of the art, has not suffered from " set-off " P From the earliest times, a " miss" on the " tympan " at hand-press meant that the one wrong deposit of ink from the forme would make itself evident on the back of the next dozen or more sheets; and who having had to deal with perfecting machines or even single-siders, when the work has to be quickly " backed up," does not know what set-off means P Try as hard as one could with oiled travelling bands, parailin-waxed rollers or other known contri- vances, one never really got rid of the difficulty of set-off. Yet it is just this kind of set-off (or offset) which has led up to a new system of getting ink on to paper and other materials, and what at one time was a curse to the printer, has come to his rescue now. In the old days referred to, a miss on the " make-ready " meant putting up a fresh sheet on the tympan, cylinder or platen. Powdered French chalk has been of great assistance among other contrivances to counteract set-off. It is practically established that the beginning of " offset " printing was when the trade was asked to print on tin or metal sheets, and this must have occurred any time between thirty and forty years ago. It was not found possible to pass a sheet of tin between the impression cylinder of a machine, and a litho stone, and gain any satisfactory result ; but when an intermediary impression cylinder covered with an india-rubber-coated blanket was introduced, it was found that the metal plate to be printed upon, would readily take up all the work laid down on the stone, after the ink had been transferred from the stone to the rubber-blanket, for the yielding surface of the rubber blanket allowed every detail to impress the surface of the plate presented to it. In case the process is not yet made sufficiently clear to all readers, it may be as well to present here the first diagram. It is that of a fiat-bed tin- plate printing machine, and is practically identical with a flat-bed offset machine of the present day. It resembles in all particulars an ordinary lithographic machine, with 212