In the department of Biography several specimens have already been given, and others are in preparation. The LIVES AND DISCOVERIES of the three celebrated English Navigators, DRAKE, CAVENDISH, AND DAMPIER, are, as already mentioned, comprised in the fifth volume; in which is embodied much curious information relative to the romantic spirit of maritime enterprise by which their times were distinguished, and a picturesque Narrative is given of the daring adventures of the BUCCANEERS. The LIFE OF SIR WALTER RALEIGH, in the eleventh volume, belongs to the same class with the preceding; for, while it includes a view of the most important transactions in the reigns of Elizabeth and James I., interspersed with Sketches of contemporary public characters, it also details his nautical achievements, and unravels certain obscurities in his history, both as a statesman and a navigator, that have not hitherto been explained or understood. The TRAVELS AND RESEARCHES OF BARON HUMBOLDT, one of the most eminent naturalists of the present day, fall likewise under this head; and, accordingly, the tenth volume has been devoted to an analysis of the journeys and scientific labours of that illustrious philosopher, who has perhaps done more than any living author to extend the boundaries of physical knowledge. In preparing this work, application was made to M. de Humboldt himself, who kindly pointed out sources of information to the Editor. In addition to these works will follow a Series of "LIVES OF CELEBRATED NATURALISTS" in all the different branches of the science. The first volume of the LIVES OF EMINENT ZOOLOGISTS, being the sixteenth of the LIBRARY, is now published, extending from the times of ARISTOTLE to those of LINNAEUS inclusive, and containing Introductory Remarks on the study of Natural History and the progress of Zoology. The second volume, already in preparation, will be devoted to the most distinguished writers in the same department, from PALLAS, BRISSON, and BUFFON, down to CUVIER,--and will conclude with General Reflections on the present state of the science. It is intended to offer to the public similar Memoirs of the principal Cultivators of BOTANY, MINERALOGY, and GEOLOGY; so that the Series, while forming a useful introduction to the study of those branches of knowledge, will also present a succession of biographical narratives, which, independently of their scientific details, cannot fail to prove extremely interesting to all classes of readers. * * * * *