BY G. R. PUTNAM, M.S. MEMBER OF THE AMERICAN SOCIETY OF CIVIL ENGINEERS DIRECTOR OF COAST SURVEYS, PHILIPPINE ISLANDS, 1900 TO 1906 FIRST EDITION FIRST THOUSAND NEW YORK JOHN WILEY & SONS London : CHAPMAN & HALL, Limited 1908 Copyright, 1908, by G. R. PUTNAM Stanhope Press F. H. GILSON COMPANY BOSTON, U.S.A....

In preparing the material for a lecture on Charts for Columbia University, the writer was impressed with the fact that although nautical charts are mentioned or discussed in many publications, there was not found any one which covered the general subject of their origin, construction, and use. In the countries of the world more than a million copies of such charts are now issued annually. A considerable portion of the human race is interested directly or indirectly, whether as mariners or passen

Periplus, an Essay on the Early History of Charts, and Sailing Directions. A. E. Nordenskiöld, Stockholm, 1897. Maps, their Uses and Construction. G. James Morrison, London, 1902. Charts and Chart Making. Lieut. John E. Pillsbury, U.S.N., in Proceedings U. S. Naval Institute, 1884 . Principal Facts relating to the Earth's Magnetism. L. A. Bauer, in U. S. Magnetic Declination Tables, Coast and Geodetic Survey, 1903. Marine Hydrographic Surveys of the Coasts of the World. G. W. Littlehales, in Rep

Need of maps. Maps are useful and necessary for many purposes. Only by means of a correct map or globe can a clear idea of the geography of a region be given. An attempt to convey the same information by a written description would in comparison be both cumbersome and obscure. Even by passing over an extensive region a man unaided by instruments will obtain only a rather crude notion of the relations, which he could clearly see on a good map. The importance among the human arts of the making of

Need of thorough surveys. As has been stated, a good chart requires that a thorough and correct survey be first made of the region to be charted. It is said that men are very apt to accept as true anything they see on a map. As to the nautical chart the mariner is likely to be somewhat more critical, however, and it is well that he is. The difficulty of charting an invisible surface such as the bottom of the sea is great, and the proportion of the navigable waters surveyed in sufficient detail t

Chart schemes. Before commencing the preparation of a chart it is necessary to arrange a definite scheme for it, and the usefulness of the chart will depend materially on this preliminary plan, in which must be outlined its scale, size, limits, and features to be represented. New charts have sometimes been prepared simply to fit the surveys as they progressed or to fill immediate or local requirements. It is, however, desirable that general plans for series or groups of charts be made, and with

Methods of publication. An ideal process of publication for nautical charts would include the following features; rapidity in getting out new charts, facility in reprinting and correcting existing charts, clearness and sharpness of print, durability of paper and print, and correctness of scale. It is difficult to fulfill all these requirements by any method as yet developed. In the Coast and Geodetic Survey several different processes are in use at present; charts are engraved on copper and prin

Need for revision. The making of the survey and the printing of the chart do not complete the problem of the chart maker. Both nature and man are constantly changing the facts the representation of which has been attempted on the charts, and also the needs of man are always varying. The original surveys are made to meet the reasonable requirements of the time, but breakwaters and jetties are built, and channels and harbors dredged and otherwise improved, and cities built, and new paths of commer

Reading charts. A chart is a representation on paper of hydrographic and topographic information by means of various conventional methods and symbols. It is evidently important for those making use of charts to understand the system and conventions used, and to be able to interpret readily the various parts of the chart. The ability to read a chart must include an understanding of all its features, such as scale, projection, geographic position, directions, depths, plane of reference, aids to na

Chart working. In crossing the open and deep portions of the ocean, where the only data given may be the projection lines and soundings far deeper than can be reached with navigational sounding machines, the chart is used to lay out in advance the general course to be followed and to plot the positions of the vessel at intervals either as determined by observations or, lacking these, by dead reckoning. When necessary the courses of the vessel are modified as the plotted positions are found to fa

There are several publications in book and in chart form which are either necessary or convenient for use in connection with nautical charts. These comprise the coast pilots, notices to mariners, tide tables, light and buoy lists, and various special charts. Coast pilots , or sailing directions, are books giving descriptions of the main features, as far as of interest to seamen, of the coast and adjacent waters, with directions for navigation. They contain much miscellaneous information of value