1. They are copies, by printing, from stereotype plates. 2. These stereotype plates are copied, by the art of casting, from moulds formed of plaster of Paris. 3. These moulds are themselves copied by casting the plaster in a liquid state upon the moveable types set up by the compositor. [It is here that the union of the intellectual and the mechanical departments takes place. The mysteries, however, of an author's copying, form no part of our enquiry, although it may be fairly remarked, that, in numerous instances, the mental far eclipses the mechanical copyist.] 4. These moveable types, the obedient messengers of the most opposite thoughts, the most conflicting theories, are themselves copies by casting from moulds of copper called matrices. 5. The lower part of those matrices, bearing the impressions of the letters or characters, are copies, by punching, from steel punches on which the same characters exist in relief. 6. These steel punches are not themselves entirely exempted from the great principle of art. Many of the cavities which exist in them, such as those in the middle of the punches for the letters a, b, d, e, g, etc., are produced from other steel punches in which these parts are in relief. We have thus traced through six successive stages of copying the mechanical art of printing from stereotype plates: the principle of copying contributing in this, as in every other department of manufacture, to the uniformity and the cheapness of the work produced. NOTES: 1. The late Mr Lowry. 2. I posses a lithographic reprint of a page of a table, which appears, from the from of the type, to have been several years old. 3. The construction of the engraving becomes evident on examining it with a lens of sufficient power to show the continuity of the lines. 4. The Phalaena pardilla, which feeds on the Prunus padus. 5. Some of these weights and measures are calculated from a statement in the Report of the Committee of the House of Commons on Printed Cotton Goods; and the widths of the pieces there given are presumed to be the real widths, not those by which they are called in the retail shops. Chapter 12 On the Method of Observing Manufactories 160. Having now reviewed the mechanical principles which regulate the successful application of mechanical science to great establishments for the production of manufactured goods, it remains for us to suggest a few enquiries, and to offer a few observations, to those whom an enlightened curiosity may lead to examine the factories of this or of other countries.