DERIVATIONS OF THE SCIENTIFIC TERMS IN GENERAL USE, TOGETHER WITH THE HISTORY AND DESCRIPTIONS OF THE PREFACE. THE DICTIONARY of SCIENCE, LITERATURE, and ART was designed to supply a want which could not be met by the larger Encyclopædias of modern times. Works of so vast an extent as the Encyclopædia Britannica or the Encyclopédie Française are too expensive for general circulation, while from their size they cannot well serve as manuals. On the other hand, Special Dictionaries, though they may exhaust some one branch of learning, are not intended to supply information on others; and thus a work like the present, possessing the comprehensive character of a general Encyclopædia without its amplitude, and affording in a convenient form an abstract of the principles of every branch of Science and an explanation of the various terms ordinarily met with in Literature and Art, still appeared to be wanting. The first edition of the present work was, therefore, offered to the public as a compendious Dictionary of a convenient size, adapted to the wants and means of all classes, and furnishing within comparatively narrow limits precise and accurate information on the all but infinite variety of subjects which it embraces. Great pains were taken to make the definitions clear, correct, and concise, and to insure a method of treatment which, though brief and compendious, should be neither flimsy nor superficial. No statement was made on doubtful matters without pointing out the source from which it had been derived; while the references given to the best works on all subjects of importance enabled the reader to extend his enquiries at will. The first edition of this Dictionary was published twenty-four years ago. The period which has since elapsed has been marked by great progress in almost every department of human knowledge. The limits and relations of the Physical Sciences have been more accurately determined, and the area of research in each has been greatly extended and more carefully scrutinised. The discovery of new objects has led to the invention of new names, and the accumulation of facts has in many cases modified or exploded theories which had gained general acceptance. Experience has justified the claims of Political Economy to the rank of a science; while the examination of the laws of evidence has strengthened, if it may not be rather regarded as having called into existence, the science of Historical Criticism. The analysis of Language has produced results of the utmost importance, not merely affecting the classification of dialects, but throwing light on many stages in the earliest developement and history of the human mind, and on many subjects of the highest interest connected with the legends and poems, the laws and society of pre-historic ages. With such changes as these, it was obviously impossible that any dictionary compiled more than twenty years ago could meet the wants or adequately represent the knowledge of the present day, while any attempt to remedy the defect by mere corrections and supplements would probably render the book even less satisfactory to the general than to the scientific reader. To the latter the additional information given in a new edition might be technically useful, while his professional experience would have made him acquainted with the progress of knowledge in his own department. The more general reader would need to be informed not merely of new facts, but of the degree in which these facts have modified the character or tendency of each particular science. In a dictionary designed to give a clear but strictly succinct account of the principles of all sciences in a way which should be acceptable both to general readers and special students, this requirement could not be met except at the cost of re-editing and re-writing the work throughout. Thus re-written, the present edition is offered to the public as substantially a new work. previous editions, the several departments under which the subjects are arranged have been intrusted to writers who have devoted themselves to the special topics respectively assigned to them. The Editors believe, therefore, that the work may be consulted with confidence by all who wish to make themselves acquainted with the principles of each particular science, with the details and history of many, and with the main facts of the many subjects with which it |