The work originally published under the title of The New American Cyclopaedia was completed in 1863, since which time the wide circulation which it has attained in all parts of the United States, and the signal developments which have taken place in every branch of science, literature, and art, have induced the editors and publishers to submit it to an exact and thorough revision, and to issue a new edition entitled The American Cyclopaedia.

Within the last ten years the progress of discovery in every department of knowledge has made a new work of reference an imperative want. The physical sciences have revealed unexpected and important relations in the material world. Chemistry and physiology have been well nigh reconstructed. Light, heat, and force are now subjected to new processes of study, with results truly astonishing. The elements of matter have undergone a fresh analysis, and are arranged in new classifications; the spectroscope has made known the intimate composition of the stars, and opened the secular history of the sun; while the researches of the physiologist and the microscopist have won brilliant victories in the field of animated nature. No less remarkable advances have been made in ethnology, archaeology, and history. The records of antiquity have received a new interpretation, and a wonderful light has been thrown upon the annals of our race.

The movement of political affairs has kept pace with the discoveries of science, and their fruitful application to the industrial and useful arts and the convenience and refinement of social life. Great wars and consequent revolutions have occurred, involving national changes of peculiar moment. The civil war of our own country, which was at its height when our last volume appeared, has happily been ended, and a new course of commercial and industrial activity has been commenced. The second French empire has perished, and the third French republic has been proclaimed amid the perturbations of one of the greatest conflicts described in history. A new German empire has been created by the same mighty convulsion; the Spanish monarchy has fallen, and a republic for the first time has been founded on Spanish soil. Austria, defeated by Prussia, has been reconstructed on a new basis. Italy has been united in one kingdom, with Rome for its capital, and the temporal power of the Pope completely overthrown.

Japan has experienced one of the most remarkable of revolutions, and significant changes have occurred in China and in other parts of Asia. Large accessions to our geographical knowledge have been made by the indefatigable explorers of Africa, and a new impulse has been given to human activity on that continent by the discovery of gold and diamonds.

The great political revolutions of the last decade, with the natural result of the lapse of time, have brought into public view a multitude of new men, whose names are in every one's mouth, and of whose lives every one is curious to know the particulars. Great battles have been fought and important sieges maintained, of which the details are as yet preserved only in the newspapers or in the transient publications of the day, but which ought now to take their place in permanent and authentic history. Since the completion of our first edition, the decennial censuses of the United States and of Great Britain have been taken, as well as many other censuses throughout the world, and the statistics of population, commerce, manufactures, and other branches of industry, that were correct at that time, have.been superseded by new material.

In preparing the present edition for the press, it has accordingly been the aim of the editors to bring down the information to the latest possible dates, and to furnish an accurate account of the most recent discoveries in science, of every fresh production in literature, and of the newest inventions in the practical arts, as well as to give a succinct and original record of the progress of political and historical events.

The work has been begun after long and careful preliminary labor, and with the most ample resources for carrying it on to a successful termination. Several of the most experienced and competent of the writers of the original work have been employed as revisers, and the assistance of new contributors of eminent distinction in their respective departments has been secured, in addition to that of members of the former corps. Only such portions of the original matter have been retained as were found to be in accordance with the existing state of knowledge; every statement has been compared with the latest authorities; every error that could be discovered by the most careful scrutiny has been corrected; many emendations in arrangement and style have been introduced; all apparent superfluities in subject and treatment have been retrenched; a multiplicity of new titles, most of which have sprung up since the issue of the first edition, have been added; while those which have become obsolete, or which were found to have lost most of their former importance, have been made to give place to others of fresher interest and unquestionable value.

None of the original stereotype plates have been used, but every page has been printed oh new type, forming in fact a new Cyclopaedia, with the same plan and compass as its predecessor, but with a far greater pecuniary expenditure, and with such improvements in its composition as have been suggested by longer experience and enlarged knowledge.

The illustrations which are introduced for the first time in the present edition have been added not for the sake of pictorial effect, but to give greater lucidity and force to the explanations in the text. They embrace all branches of science and of natural history, and depict the most famous and remarkable features of scenery, architecture, and art, as well as the various processes of mechanics and manufactures. Although intended for instruction rather than embellishment, no pains have been spared to insure their artistic excellence; the cost of their execution is enormous, and it is believed they will find a welcome reception as an admirable feature of the Cyclopaedia, and worthy of its high character.