This volume was published by authority of the Lords Commissioners of the Admiralty, with the stated intent of making scientific and medical information available to officers in a convenient and relatively accessible manner. The Manual contains fifteen chapters on such subjects as astronomy, hydrography, meteorology, ethnology, zoology, and botany, contributed by specialists of the day, including G. B. Airy, F. W. Beechey, Edward Sabine, Sir John Herschel, Charles Darwin, Richard Owen, and William Hooker. The book first appeared in 1849, and the chapters in this third edition were revised by the authors to incorporate any new information from the intervening decade.