This text deals with meteorological instruments and the practical aspect of making observations, which are essential for the safe and economic operation of a ship. This is the first revision for over 18 years, and much of the text has been revised to reflect current practices in instrumentation and units of measurement. The chapters dealing with the observation of phenomena have been expanded to include new material on many types of marine life. Colour illustrations have been introduced and many photographs taken by officers on United Kingdom observing ships are included, notably those of the state of the sea; there is also a completely new set of cloud photographs in colour.;The book also provides a reference for candidates for certificates of Competency issued by the Marine Safety Agency of the Department of Transport. The theoretical application of meteorology to a seaman's profession is provided in the companion volume "Meteorology for Mariners".