minute in its analysis, displaying the latest development of the time-saving art of precise indexing, but will also be by far the most complete index to the general sum of human knowledge which has ever been compiled. An index thus constructed on modern lines will greatly facilitate the use of such a work as this, for its possessor will enjoy the advantages, without suffering the disadvantages, which mark a work of reference consisting of general treatises rather than of brief and fragmentary articles treating, after the manner of a dictionary, each subdivision of a subject under a separate heading. This dictionary system of treatment gives a far less readable result, and its practical convenience is no greater than that which the new volumes will offer with the aid of their elaborate index.
Other considerations which affected the size of the supplement were the need for new maps, called for by recent political changes and geographical discoveries, and also the necessity for copious illustration. The Ninth Edition was more amply illustrated than any former work of reference had been, and since its time the utility of informative illustration, as distinguished from mere pictures, has become more and more generally recognized. A picture of a machine, occupying a few square inches of space, conveys a clearer impression than a whole page of description. The new volumes are therefore even more copiously illustrated than were those of the Ninth Edition, and the 2500 separate drawings which were made will, it is believed, fully justify the great care which has been expended upon them. The portraits and reproductions of pictures which accompany the biographies of living celebrities have in important instances been chosen for this purpose by the persons themselves, and the engravings have all been executed specially for the work. Every effort has been made to conserve in the new matter the high standard of the Ninth Edition, although the articles are conceived in a spirit more modern than that which obtained a generation ago. The present demand for practical details, for the industrial as well as the theoretical point of view in treating scientific developments—a natural result of the fact that new classes of readers have been stimulated to practical research by the spread of education is another factor which contributed to the number and variety of the articles. Men who are engaged, if not literally in the manual processes of manufacture, at any rate in the immediate supervision of these processes, form a section of the reading public peculiarly exacting in their requirements. The great keenness of competition between English and foreign manufacturers furthermore makes it essential that financial, commercial, industrial, and scientific topics should not be approached from an insular and restricted point of view.
With this and many other considerations in mind, the selection of the contributors to the new volumes was a task of great delicacy. The first step was to choose the departmental editors by whom the individual contributors should in turn be nominated, and in both respects the editors believe the selections have been remarkably successful. A list of departmental editors and of contributors will be found in another part of the work, and it will be perceived that German,, French. Dutch, Italian, Spanish, Russian, and Scandinavian writers have done much to round off the comprehensiveness of these new volumes, and to bring to a wider field of examination the same spirit of accurate scrutiny which characterized the Ninth Edition. It may be doubted whether in any previous work of reference the advantages to be gained from the cosmopolitan character of the staff of contributors have been so fully attained. Absolutely no discrimination was made
