In Chapter II. an attempt has been made to explain the physical and chemical phenomena which accompany the interaction of calcium carbide and water, and to show what features in the reaction are useful and what inconvenient in the evolution of acetylene on a domestic or larger scale. Similarly in Chapter III. have been described the various typical devices which may be employed in the construction of different portions of acetylene plant, so that the gas may be generated and stored under the best conditions, whether it is evolved by the automatic or by the non- automatic system. This having been done, it seemed of doubtful utility to include in the first edition of this work a long series of illustrations of such generators as had been placed on the markets by British, French, German, and American makers. It would have been difficult within reasonable limits to have reproduced diagrams of all the generators that had been offered for sale, and absolutely impossible within the limits of a single hand-book to picture those which had been suggested or patented. Moreover, some generating apparatus appeared on the market ephemerally; some was constantly being modified in detail so as to alter parts which experience or greater knowledge had shown the makers to be in need of alteration, while other new apparatus was constantly being brought out. On these and other grounds it did not appear that much good purpose would have been served by describing the particular apparatus which at that time would have been offered to prospective purchasers. It seemed best that the latter should estimate the value and trustworthiness of apparatus by studying a section of it in the light of the general principles of construction of a satisfactory generator as enunciated in the book. While the position thus taken by the authors in 1903 would still not be incorrect, it has been represented to them that it would scarcely be inconsistent with it to give brief descriptions of some of the generators which are now being sold in Great Britain and a few other countries. Six more years' experience in the design and manufacture of acetylene plant has enabled the older firms of manufacturers to fix upon certain standard patterns for their apparatus, and it may confidently be anticipated that many of these will survive a longer period. Faulty devices and designs have been weeded out, and there are lessons of the past as well as theoretical considerations to guide the inventor of a new type of generator. On those grounds, therefore, an attempt has now been made to give brief descriptions, with sectional views, of a number of the generators now on the market in Great Britain. Moreover, as the first edition of this book found many readers in other countries, in several of which there is greater scope for the use of acetylene, it has been decided to describe also a few typical or widely used foreign generators. All the generators described must stand or fall on their merits, which