[Illustration: FIG. 2. CHART OF NORTH ATLANTIC OCEAN,] Gerhard Krämer, a Flemish map-maker, better known by his Latin name of Mercator, in 1569 published his famous Universal Map. In this map the meridians and parallels were still straight lines intersecting at right angles, but the distances between the parallels were increased with increasing latitude in such proportion that a rhumb line, or line cutting the meridians at a constant angle, would appear on the map as a straight line. Mercator never explained the construction of his chart, and as the above condition was not accurately carried out, it is thought that the chart was drawn by comparing a terrestrial globe with a "plain chart." After examination of a mercator chart in 1590, Edward Wright developed the correct principles on which such a chart should be constructed, and published in 1599 his treatise "The Correction of Certain Errors in Navigation." It took nearly a century to bring this chart into use, and even in the middle of the eighteenth century nautical writers complain that "some prefer the plain chart." [Illustration: BY JUAN DE LA COSA, 1500. EARLIEST EXTANT CHART SHOWING AMERICA.] The Arcano del Mare, 1646, was the first marine atlas in which all the maps were drawn on the mercator projection. In the sixteenth, seventeenth and eighteenth centuries charts and sailing directions were often bound together in large volumes. These usually had quaint titles, not overburdened with modesty, of which the following is an example: "The Lightning Columne, or Sea-Mirrour, containing the Sea-Coasts of the Northern, Eastern, and Western Navigation. Setting forth in divers necessaire Sea-Cards, all the Ports, Rivers, Bayes, Roads, Depths, and Sands. Very curiously placed on its due Polus height furnished. With the Discoveries of the chief Countries and on what Cours and Distance they lay one from another. Never there to fore so Clearly laid open, and here and there very diligently bettered and augmented for the use of all Seamen. As also the situation of the Northerly Countries, as Islands, the Strate Davids, the Isle of Jan Mayen, Bears Island, Old Greenland, Spitsbergen and Nova Zembla. Adorneth with many Sea-Cards and Discoveries. Gathered out of the Experiences and practice of divers Pilots and Lovers of the famous Art of Navigation. Where unto is added a brief Instruction of the Art of Navigation, together with New Tables of the Sun's Declination, with a new Almanach. At Amsterdam. Printed by Casparus Loots-Man, Bookseller in the Loots-Man, upon the Water. Anno 1697. With Previlege for fiftheen years."