The British Hydrographic Office publishes eight volumes of Lists of Lights, and these are corrected annually.
Chart catalogues are published in connection with all series of charts. They give the particulars and price of each chart published, and are usually arranged in geographical order, with both alphabetical and numerical indexes, for convenience in finding charts either by position, name, or number.
Charts for special purposes. There are various special charts published for the benefit of mariners, although not intended for direct use in plotting the course of a vessel or in locating its position. Some of the more important of these are mentioned below.
Gnomonic charts are intended solely for laying down the great circle or shortest practicable courses between points, for which purpose they are very convenient. Their use has already been described. The United States Hydrographic Office publishes six such charts, for the North Atlantic, South Atlantic, Pacific, North Pacific, South Pacific, and Indian Oceans.
Current charts are published by the British Hydrographic Office for the various oceans; these usually show the average ocean currents, but for the Atlantic there are monthly and for the Pacific quarterly current charts.
Magnetic variation charts are published by both the United States and British governments. They show on a mercator chart of the world the isogonic lines, or lines along which the variation of the needle from true north is the same. The lines are drawn for each degree of variation. The annual change in the variation is also indicated.
Other magnetic charts are published showing the lines of equal magnetic dip, horizontal magnetic force, and vertical magnetic force.
Meteorological ocean charts are published by several governments, including the United States, Great Britain, and Germany, and give the average weather conditions, winds, fogs, currents, ice, tracks of storms, and other information. "Pilot charts" of the North Atlantic and North Pacific Oceans are issued by the United States Hydrographic Office about the first of each month, and give "a forecast of the weather for the ensuing and a review of that for the preceding month, together with all obtainable information as to the most available sailing and steam routes, dangers to navigation, ice, fog, derelicts, etc., and any additional information that may be received of value to navigation." Mariners in all parts of the world have joined in contributing the information which has been used in compiling these pilot charts.
Track charts are published by the British and United States governments. That of the latter is entitled "Track and distance chart of the world, showing the routes traversed by full-powered steamers between the principal ports of the world, and the corresponding distances."