Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/275

Rh NAVIGATION 263 size of the earth, as well as the means of ascertaining the latitude and longitude of innumerable places (see EARTH and GEOGRAPHY). They are now made as precisely as possible to represent the actual surface of the globe. The result of each survey is first plotted with the meridian lines inclined towards the pole, by which means all astronomical bearings coincide. It is afterwards opened proportionately to suit Mercator s projection and the sailor s use, as far as 70 or 80 degrees. For the polar regions a circular projection is used, which may comprise a radius of 30 or even 40 degrees. During 1882 sixty-one new plates of charts were engraved, and eighteen improved by the addi tion of new plans; 2700 plates received corrections by the engraver. The number of charts printed for the royal navy, Government departments, and to meet the requirements of the general public, during 1882 amounted to 229,700. The Admiralty catalogue of charts and sailing directions now contains 2680 of the former and 83 of the latter. The tide table for 1883 gives the time of high water at all the ports in Great Britain and Ireland, also for full and change days all over the globe, upwards of 3200 in number. The cost of the hydrographic department was 43,145 last year, of which 20,958 was for surveys in various parts of the world, hire of vessels, wages, &c. Many of the early writers and teachers of navigation regretted that no national care was bestowed upon the education of navigators ; they might be rejoiced could they know that the Royal Naval College at Greenwich is main tained at a cost of 31,800; beside which there is the Naval College at Portsmouth, and the &quot; Britannia &quot; train ing ship for naval cadets, which latter costs over 17,000 a year, one half being paid by the parents. There is also a school at Greenwich for a thousand boys, the sons of petty officers, seamen, and marines, all of whom (unless physically incapacitated) are destined for the sea. There are also several training vessels connected both with the royal navy and the mercantile marine. There can be no doubt that the educational qualification of seamen of all grades is well provided for, and as little doubt that the kindred qualification &quot; seamanship &quot; is neglected ; but the examination for a lieutenant in the navy will in future include a knowledge of Channel pilotage. A meteorological conference was held in Brussels in 1853 for devising a uniform system of observations at sea, upon winds and currents; and a meteorological department was established in England soon after, under the Board of Trade and Admiral FitzRoy. In 1866 it was placed under a committee selected by the Royal Society. It is hoped that before long much useful information may result from that source. Wind and current chart? are now compiled by the Admiralty, which are very valuable aids in long voyages. At the commencement of the present century all watches designed for the discovery of the longitude were called &quot; chronometers &quot; ; they were but slowly coming into general use ; the Admiralty only supplied them to flagships, sur veying ships, and exploring expeditions. Later every ship of war was allowed one, and an additional one if the captain possessed one of his own. The East India Company allowed their ships one each at an early date. Now flagships are allowed five, and ordinary ships of war three each. Chronometers were soon recognized as a certain and simple means of ascertaining the difference of longitude between two places ; Captain Cook and others used them in the last century. Between 1817 and 1824 Captain Smyth used five chronometers in the survey of the Mediterranean. Dr Tiarks, 1822-23, used twenty- six to establish the longitude of Pendennis Castle, and for Funchal, Madeira, seventeen. Schubert in 1833 proceeded round the Baltic in a steam-vessel with fifty-six chrono meters, reckoning his longitude from Altona. In 1826 King carried eleven in the &quot;Adventure&quot; and &quot;Beagle ; Foster in 1828, seventeen in the &quot;Chanticleer&quot;: FitzRoy, 1831, twenty -two in the &quot;Beagle.&quot; In 1839 Lieutenant Raper proposed that eighteen &quot; secondary meridians should be established, and, these being well spread over the globe, the minor places should be referred to them, and not to each other as formerly. There are now fifty such secondary meridians, and the electric wire has taken the place of the timekeeper, as the time-signal is the most perfect thing which human ingenuity can devise. The elaborate chronometric expeditions of English, Continental, and American astronomers belong rather to the history of astronomy. When the Atlantic cable was laid to New foundland in July 1866, and time-signals received direct from Greenwich Observatory to Heart s Content, the Admiralty chart was found to be quite correct. In a similar manner all the principal places in North and South America and the West India Islands have been connected by time-signals with the United States observatories within the last seven years, and found to be fairly correct, the error seldom amounting to two seconds in time. The observatory at Lisbon was found to differ eight seconds of time. It may now be assumed that there is no place within the ordinary navigable parts of the ocean where an error in position exists of sufficient amount to affect a ship s safety. A reward was formerly given annually to the maker of the chronometer which stood the best test at the observa tory; this was instituted in 1822, and discontinued after 1835; the recipients were Poole, Frodsham, Hutton, Hewett, Eiffe, and Dent, Since that time they are re ceived at the observatory on trial during twenty-eight weeks, and those preserving the most equal rate are chosen for the public service at a price named by an official in charge of the department, and something above the ordin ary price. Prior to 1849 as much as 62 was paid for one; in 1883 about six are recommended for purchase at 45 to 38 each. On Dent s catalogue marine chrono meters range from 35 to 45 guineas. The following list of some writers of navigation whose works have not been already mentioned may be found useful : Thomas Addi- son, Arithmetical Navigation, 1625 (he was the first to apply logarithms); Antonio de Najera (Lisbon, 1628) follows Xunez and Cespedes, but corrects the declination of sun and stars ; Sir E. Dudley, L arcano del mare, 1630-46, 2cl eel., Florence, 1661, too ponderous for the use of seamen ; Sir Jonas Moore (1681), one of the best books of the period ; William Jones (1702), a useful compendium containing trigonometry applied to the various sail ings, the use of the log, and tables of logarithms ; Pierre Jean Bouguer, Traitt Complet de la Navigation, folio, 1698, good but too large ; Manuel Pimental, L arte dc navegar, Lisbon, 1712 ; Pierre Bouguer, jun., Nouvcau Traite dc Navigation, 1753 (without tables), published at the request of the minister of marine, im proved and shortened in 1769 under the superintendence of the astronomer Lacaille ; Nathaniel Colson, The Mariners New Calen dar, 1735, a good book ; Seller, Practical Navigation, a book very popular in its time (there was an edition as late as 1739) ; Samuel Dunn published good star charts and tables of latitude and longitude (1737), and framed concise rules for many problems on navigation (published by the board of longitude) ; John H. Moore, The Practical Navigator ami Seaman s New Daily Assistant, 1772, very popular, and generally used in the British navy, the 18th and 19th editions (1810, 1814) were improved by J. Dessiou ; W. Wilson (Edinburgh, 1773), a treatise of good repute at the time ; Samuel Dunn, New Epitome of Practical Navigation, or Guide to the Indian Seas, 1777, for the longitude he depends chiefly on a variation chart from observations on East Indiamen, and he still makes no mention of the Nautical Almanac or of parallel rulers ; Samuel Dunn (probably a son of the last named), 1781, is the last vriterwho gives instructions for the use of the astrolabe; he also wrote on &quot;lunars&quot; (1783, 1793), _ a word which was generally adopted about this time, and published an excellent traverse table (1785), and Daily Uses of the Nautical Sciences, 1790 ; Horsborough, Directory for Hast India Voyages, 1805 ; A. Mackay, The Complete Navigator, about 1791, 2d ed. 1810, there is no instruction for finding longitude by the time.