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 all sections of our extended coast line petitioning for surveys at the same time, the problem was beset with additional difficulties. Fortunately Congress prescribed the method on which the work should be conducted, and that the method permitted making surveys widely separated with the certainty that they could eventually be joined and form a consistent whole. Soon after the plan of reorganization of 1843 had been adopted, surveying parties were on the Atlantic and Gulf coasts at many points; the principal harbors and headlands with outlying shoals were first surveyed and it was but a few years before charts of them were published. The less important shores between these points were left for future work, but Hydrographic examinations or Nautical surveys, were made of them, and preliminary charts of long stretches of coast were issued, to be followed when the surveys had been completed by the finished chart of reliable data. So elastic was the system adopted for the conduct of the work, that its availability was limited only by the annual appropriations. Soon after the annexation of Texas surveying parties were on that coast, and on the acquisition of California a few years subsequently parties were soon at work there also; and after the close of the war and purchase of Alaska, the immense field thus opened was attacked with equal promptness, and a reconnaissance made that resulted in a map of considerable accuracy. As the precise surveys were extended the charts and plans published from the preliminary surveys were withdrawn, the new charts necessarily having later dates.

The original surveys of the Atlantic and Gulf coasts are now practically completed, but very little more remaining to be done in a few comparatively unimportant localities. On the Pacific coast precise surveys supplemented by careful reconnaissance of less important sections, define nearly the whole outline, excepting Alaska, but a great deal of work is still required to obtain the full measure of information necessary to accurately chart it. And in Alaska, Nautical surveys have developed long stretches of the "Inland passage " and the most important anchorages, supplementing the general reconnaissance of the whole coast line. A very large proportion of our shores, however, are subject to such radical changes from natural causes, that the survey of the coast can never be brought to final completion. Examinations and re-surveys are as essential as was the original work, if the material already acquired is to be maintained in the full measure