16005 m.C.T. EDITOR'S ADVERTISEMENT. IN N issuing this Subscription Edition of the ENCYCLOPÆDIA BRITANNICA, two objects have been kept mainly in view,-in the first place, to secure perfect accuracy of reproduction; and, in the second, to do this at a cost so moderate as to place the work within the reach of the public at large. These ends have, it is believed, been attained in the edition now offered to the American people. To secure absolute correctness in the reproduction both of letterpress and illustrations, this work has been printed from the original stereotype plates of the English Edition. In all essential respects, therefore, the work as issued in the two countries is the same. A word or two may be added as to the special features which make the Ninth Edition of the Encyclopædia a considerable advance on the last. In reconstructing the work so as adequately to meet the requirements of advancing knowledge, it was found necessary, while retaining its main outlines, to modify and enlarge the original plan. The modifications are seen in the greater number of headings devoted to Science in its two great departments of Physics and Biology. The new features will be found chiefly under the heads of Literature, History, and Philosophy. In relation to the first, the present edition will contain an historical outline and review of all the literatures of the world, both in ancient and modern times. I may point to the articles on American, Celtic, Chinese, English, and French literature, as illustrations of this new and important feature. In the department of History, special attention has been given to the most fruitful branch of modern inquiry and research-the history of early culture, the growth and gradual development of primitive ideas, laws, customs, and institutions, as well as to the conditions and principles of social progress in historical and civilized communities. In a word, every effort has been made to represent in outline the circle of inquiries included in the modern sciences of Anthropology and Sociology. In the biographical section, all the more important names connected with science, literature, and public life find a place. But this rule applies only to the completed record of illustrious lives, contemporary names being excluded, as, apart from the invidious task of selection, any attempt to deal, even in outline, with living men of eminence would have seriously changed the character of the work. In Mental Philosophy and the important topics connected with Biblical Criticism, Theology, and the Science of Religion, the distinctive change in the new Edition relates to the method of treatment. In the first place, these subjects are dealt with at greater length, in harmony with the keen, intelligent, and general interest now concentrated upon them. In the second place, they are uniformly looked at from the critical and historical rather than the dogmatic point of view, as that best fitted both to the character of the work and the requirements of the modern reader. In relation to all important points still under discussion, the aim is to give a full and impartial outline of the actual state of the question. These lines have I believe, been carefully followed in the volumes already published, and they will, as far as possible, be faithfully adhered to in those which are to come. In enumerating some of the features of the new Edition, it may be added that special attention has been devoted to the Geography, History, and Institutions of America, and that to obtain thoroughness and accuracy in this department, the services of well-qualified American writers have, as a rule, been secured. This was, indeed, essential to the character and air of the work as an authoritative book of reference for English-speaking communities in every quarter of the globe. PREFATORY NOTICE. TH HE ENCYCLOPÆDIA BRITANNICA has long deservedly held a foremost place amongst English Encyclopædias. It secured this position by its plan and method of treatment, the plan being more comprehensive, and the treatment a happier blending of popular and scientific exposition than had previously been attempted in any undertaking of the kind. The distinctive feature of the work was that it gave a connected view of the more important subjects under a single heading, instead of breaking them up into a number of shorter articles. This method of arrangement had a twofold advantage. The space afforded for extended exposition helped to secure the services of the more independent and productive minds who were engaged in advancing their own departments of scientific inquiry. As a natural result, the work, while surveying in outline the existing field of knowledge, was able at the same time to enlarge its boundaries by embodying, in special articles, the fruits of original observation and research. The Encyclopædia Britannica thus became, to some extent at least, an instrument as well as a register of scientific progress. This characteristic feature of the work will be retained and made even more prominent in the New Edition, as the list of contributors already published sufficiently indicates. In some other respects, however, the plan will be modified, to meet the multiplied requirements of advancing knowledge. In the first place, the rapid progress of science during the last quarter of a century necessitates many changes, as well as a considerable increase in the number of headings devoted to its exposition. In dealing with vast wholes, such as Physics and Biology, it is always a difficult problem how best to distribute the parts under an alphabetical arrangement, and perhaps impossible to make such a distribution perfectly consistent and complete. The difficulty of distribution is increased by the complexity of divisions and multiplication of details, which the progress of science involves, and which constitute indeed the most authentic note of advancing knowledge. This sign of progress is reflected in extensive changes of terminology and nomenclature, vague general headings once appropriate and sufficient, such as Animalcule, being of necessity abandoned for more precise and significant equivalents. But. since the publication of the last edition, science, in each of its main divisions, may be said to have changed as much in substance as in form. The new conceptions introduced into the Biological Sciences have revolutionised their points of view, methods of procedure, and systems of classification. In the light of larger and more illuminating generalisations, sections of the subject, hitherto only partially explored, have acquired new prominence and value, and are cultivated with the keenest interest. It is enough to specify the researches into the ultimate structures, serial gradations, and progressive changes of organic forms, into the laws of their distribution in space and time, and into the causes by which these phenomena have been brought about. The results of persistent labour in these comparatively new fields of inquiry will largely determine the classifications of the future. Meanwhile the whole system of grouping, and many points of general doctrine, are in a transition state ; and what is said and done in these directions must be regarded, to a certain extent at least, as tentative and provisional. In these circumstances, the really important thing is, that whatever may be said on such unsettled questions should be said with the authority of the fullest knowledge and insight, and every effort has been made to secure this advantage for the New Edition of the Encyclopædia. The recent history of Physics is marked by changes both of conception and classification almost equally great. In advancing from the older dynamic to the newer potential and kinetic conceptions of power, this branch of science may be said to have entered on a fresh stage, in which, instead of regarding natural phenomena as the result of forces acting between one body and another, the energy of a material system is looked upon as determined by its configuration and motion, and the ideas of configuration, motion, and force are generalised to the utmost extent warranted by their definitions. This altered point of view, combined with the far reaching doctrines of the correlation of forces and the conservation of energy, has produced extensive changes in the nomenclature and classification of the various sections of physics; while the fuller investigations into the ultimate constitution of matter, and into the phenomena and laws of light, heat, and electricity, have created virtually new sections, which must now find a place in any adequate survey of scientific progress. The application of the newer principles to the mechanical arts and industries has rapidly advanced during the same period, and will require extended illustration in many fresh directions. Mechanical invention has, indeed, so kept pace with the progress of science, that in almost every department of physics improved machines and processes have to be described, as well as fresh discoveries and altered points of view. In recent as in earlier times, invention and discovery have acted and reacted on each other to a marked extent, the instruments of finer measurement and analysis having directly contributed to the finding out of physical properties and laws. The spectroscope is a signal instance of the extent to which in our day scientific discovery is indebted to appropriate instruments of observation and analysis. These extensive changes in Physics and Biology involve corresponding changes in the method of their exposition. Much in what was written about each a generation ago is now of comparatively little value. Not only therefore does the system of grouping in these |