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'TRAE. Marine REVIEw 29 it is clear that this service is one for which the navy is par- ticularly well adapted in times of peace--a service which, in general, can be performed without interfering with other naval requirements, and with results which inure to the benefit of all mankind. And it is a pleasure to state that the service is one which is not considered distasteful in the navy. Frequently, due to the exigencies of diplomatic rela- tions and for other reasons our vessels aze stationed in for- eign waters for long intervals of time, during which the officers and crews generally welcome surveying work as a decided break in the monotony of their confinement to the limits of the ship. In addition to the resulting benefit to our maritime inte:--- ests, the naval service is also materially benefited. The work tends to bring out the officer's powers of observation of things nautical, and to give him a familiarity with coast work which becomes invaluable in time of war. This was well exemplified during our civil war when the most suc- cessful blockade runners wee commanded by men--gen- erally ex-naval officers--who had been. engaged in the coast survey in the vicinity of their blockading operations.. Now as to chart construction. In general a preliminary sheet of the work done, prepared with accuracy and with a sufficient degree of delicate draftsmanship to clearly dem- _ onstrate any inaccuracies as the work progresses, together with the records of astronmical observations, triangulation, topography, tides, currents, etc., is forwarded from the -sur- veyinig vessel to the Hydrographic Office, where in the di- vision of chart construction, now presided over by one 'of the most thoroughly equipped hydrographic engineers in: this or any country, the work is carefully revised in every detail and a smooth sheet prepared, from which comes the working chart either from an engraved copper-plate or by a litho- -- graphic process. As soon as the finished chart is printed, all vessels of the navy serving' in the locality which it in- dicates are supplied therewith. The merchant vessels of all nations can obtain.it by purchase from the Hydrographic Office or 'from any of its numerous agents. As soon as received in the Hydrographic Office the work is made a matter of record and the history of the chart com- mences, not to end until the chart becomes obsolete or is cancelled by another. Every correction, alteration, or ad- dition, with the names of all connected therewith, becomes a matter of record which is carefully guarded. While some- times, for good and sufficient reasons, the legend on the chart does not show the authority, that information is on its. record. Generally speaking, navigational charts are of three classes; General charts, coast charts and harbor, charts, the coast charts occasionally being divided into special and general. - General charts, as the name implies, cover a large territo-y, and are principally for the use of navigators in the open sea as in making long voyages. On this chart the navigator plots his geographical positions as often as they are determined, and thus is able to keep as nearly as possible a direct course to his port of destination. This chart is kept in use until the vessel gets within the limits of the coast chart, when it is put away and replaced by the latter. oe Coast charts, both general and special, delineate the coasts of all countries, and for each coast are consecutive and take in such sections of the coast as will permit. of. the use of a comparatively large scale. The coast line is ac- curately delineated, as are also the principal topographical features which can be used in navigation; all the light- houses, with their peculiar characteristics; the lifesaving sta- tions, weather bureau stations, and all the features which in any way can enable an observer by bearings, or otherwise, to determine his position. The soundings are frequent and, in general, are run out to the 100-fathom curve. With the aid of this coast chart, the navigator pilots his ship along shore until within the limits of the chazt of the harbor. to which he is bound, when that replaces it. -- The harbor chart is on a larger scale than the others men- tioned and in greater detail. Every object on shore that can be used in piloting the ship in or out of the harbor is delineated. in its correct position. Where possible ranges "to . guide vessels in and out are determined and plotted upon the chart; lighthouses, range lights,. buoys, beacons, and all day- marks are plotted; the positions of landing places, custom- houses and public buildings of which the navigator may have occasion to know are plotted where possible ; curves of certain equal depths of water, quatantine stations and quarantine grounds, men-of-war and merchant ships' anchor- ages are also clearly indicated; the magnetic declination or variation is noted on one or more compass roses and, in addition, the chart contains all necessary data as to the date of publication, the date of the latest correction, the char- acter of the soundings, heights, signs and abbreviations and all necessary tidal information. On these cha:ts as on coast charts the shore lines are made especially conspicuous and the topographical features represented are such as will be of actual value as aids to the navigator. At the present time the Hydrographic Office has in its pos- _ session "nearly 1,200 engraved chart-plates and about fifty photographic cha:t- plates. These 1,250 plates have all 'been constructed from the results of original naval surveys; from _ geographical and cartographical data reported by the com- _manding officers of vessels in the naval service; and from information collected by the bsanch hydrographic offices, from in- coming mariners of all nationalities, and also from the geographical information that comes into the custody of the navy department through the prosecution of surveys by foreign. governments. Besides the projecting, drawing, engraving, pébterant ing, electrotyping and printing which constitute the central work of chart construction and chart correction, the func- tions of the Hydrographic Office also include the mathe- matical computations for the projection, the adjustment of triangulations, the investigations of the tides, the discus- sion of observations of the magnetic elements of the earth in their bearing upon charts and navigation; the computa- tion of navigational tables, and the designing of instruments and machines for securing the maximum of economy. Of the 1,250 os more charts that are now available for per- manent issue, over 300 have been derived from original sur- veys by the United States navy. These added to the 450 or more charts that have been constructed from surveys by the Coast and Geodetic Survey make a grand total of 750 navigational charts constructed from oziginal United States surveys, a result which places our people ahead of most of the older countries and in the front rank of the most active nations in marine hydrographic work. Our knowledge of the depths of the' sea is gradually in- creasing through the operations of deep-sea sounding expe- ditions undertaken by many nations. In this field of opera- tion we hold a commanding position. From a scientific point of view a knowledge of the physical characteristics of the ocean bed is most desirable, and no less so from a practical standpoint. No telegraph company would think of laying a submarine cable today without first selecting a desirable route as determined by deep-sea 'soundings. the soundings of the U. S. 5.. Nero in the Pacific three years ago determined the route since selected for the trans-Pacific cable, and the pos- session of these soundings went a long way toward enabling our Government to name and obtain its own requirements from the cable company, Deep-sea soundings are also of