Before entering on the description of the several quarters of the globe, it will be convenient for the student to possess the following table of the latitude and longitude of some of the most remarkable towns, capes, &c. collected from the latest and most accurate observations. In this table the longitude is reckoned not from the meridian of London, but from that of the observatory erected on the summit of the hill in Greenwich Park, which being the station of the Astronomer Royal, (at present the eminent Dr. Nevil Maskelyne,) where a regular system of celestial observation is carried on, and to which all calculations relating to geography, navigation, and astronomy are referred, it has for a considerable time been determined, that the first meridian should be that which passes over this observatory. The difference of longitude between the observations of Greenwich and Paris having been carefully ascertained to be 2°, 19', 51", the student will have no difficulty in reducing longitudes calculated for the meridian of Paris, as in the French maps and sea-charts, to the meridian of Greenwich, and vice versa; for Paris being situated 2°, 19, 51'to the eastward of Greenwich, if the longitude be given east from Paris, the above difference must be added to obtain the longitude from Greenwich; but if the given longitude be west from Paris, this difference must be subtracted: thus, if Rome be situated in longitude east from Paris 30°, 7', 40", by adding the difference we have 32°, 27, 31" for the longitude of Rome east from Greenwich; again, if the Royal Marine Observatory in Cadiz be situated in longitude west from Paris 8°, 37, 35", by btracting the above difference we have 6, 17, 44" for the longitude of Cadiz west from Greenwich. By means of this difference of longitude between Greenwich and Cadiz, all longitudes reckoned from this last place, as is done in the modern Spanish maps and charts, may, a similar way, be reduced to the meridian of Greenwich. in TABLE |