Offset and Offset Machinery its inkers, dampers and impression cylinder, but there is the addition of the extra cylinder, practically all that is necessary to turn it into an offset machine. Instead of the sheet going between the lower of the two cylinders, that is, between the blanket and the stone, it is taken by the grippers of the upper cylinder and receives the ink from the rubber blanket on the lower cylinder, picked up by its contact with the stone. In offset printing, the Work or design has to be laid down on the stone in a different manner from ordinary lithography; because, as types or letters are cast in the obverse, and litho-work is transferred from the original writing, or written backwards on stone, by the double process it becomes necessary to write, or lay down the work on the stone or plate in the positive, just as an ordinary letter, drawing, or manuscript. The first impression oif the stone is on to the rubber blanket, and of course reverses the work; now the passing of the ink on to the paper again reverses the work, pre- senting it just as it was originally written. In transfer work it is, of course, obvious that the impression from the type or writing on transfer-paper reverses the subject-matter; and the re-transfer on to stone puts it back into the correct form for its printing on metal or paper. S0 much for the process, which I hope I have neither elaborated too much or failed to make clear. It is only a short period since rotary offset machines have been offered to the trade as a substitute for lithography, and this was made easy when zinc and aluminium plates took equal place with lithostones. The thin 213