Books are almost universally printed on what is called the flat-bed machine, so-called because the types or plates are placed on an iron table which with them travels to and fro under a series of revolving rollers constantly being fed with a supply of ink which they transfer to the types or plates. Immediately these get beyond the inking rollers they pass under a revolving cylinder with a set of grippers attached, which open and shut with each revolution. These grippers take hold of the sheet of paper and carry it round with the cylinder. When it comes in contact with the types or plates travelling underneath, the impression or print is made. Some machines complete the printing of the sheet on both sides at one operation. In others the sheet is reversed and is printed on the other side by passing through a second time. In either case the sheet forms only a section of a book; the complete volume is made up of a number of these sections, folded and collated in proper order in the bindery. There they are sewn together and fixed in the case or cover. For illustrated books the pictures were formerly produced by engraving on wood, but they are now chiefly photographed from the artist's drawing on a light sensitive film spread on a metal plate, and etched in by acids. In whatever way produced, when printed with the text they are always relief blocks which are placed in proper position in the chase alongside the types or plates. Coloured illustrations are produced by successive printings. Special illustrations are frequently produced separately by other processes and inserted in the volume by the binder. Machines of a different construction, such as the rotary press, and capable of a very much higher rate of production, are in use for printing newspapers and periodicals with a large circulation, but these do not properly come into consideration when telling how a modern book is made. [_The above chapter has been kindly contributed by the printers of this volume._ _G. B. R._] AUTHOR'S POSTSCRIPT. In our endeavour to note the chief points in the history of books, and in considering the manifold interests which are bound up with their bodies, we have had to neglect their minds. To have tried even to touch upon the vast subject of literature in our story would have been as futile as an attempt to transport the ocean in a thimble. For literature consists of all that is transferable of human knowledge and experience, all that is expressible of human thought on whatever matter in heaven or earth has been dreamed of in man's philosophy. And though our aggregate of knowledge be small, it is vastly beyond the comprehension of one individual being.