Cloud atlas was published in 1802. It followed a similar effort in French by Jean-Baptiste Lamarck in 1801. Howard's nomenclature defined four fundamental types of clouds: cirrus or thread-cloud, cumulus or heap-cloud, stratus or flat cloud (level sheet), and nimbus or rain-cloud (see Classification of clouds). There followed a long period of development of the field of meteorology and the classification of clouds, leading up to 1896, the International Year of Clouds. The history of this period is the subject of a popular book, "The Invention of Clouds". During that time, the Englishmen Rev. Clement Ley and Hon. Ralph Abercromby, were influential.
Sheet (sailing) flat, thin surface, such as a sheet of paper or a bed sheet. In nautical usage the term "sheet" is applied to a rope or chain attached to the lower corners of a sail for the purpose of extension or change of direction. The connexion in derivation with "shoot" is more clearly seen in "sheet-anchor", one that is kept in reserve, to be "shot" in case of emergency. Fore-and-aft rigs comprise the vast majority of sailing vessels in use today, including effectively all dinghies and yachts. The sheet on a fore-and-aft sail controls the angle of the sail to the