Barometer Normal.—The barometer normal for the 5°-square from latitude 35° to 40° N., longitude 65° to 70° W., assumed for the present purpose as the normal for the entire area, is 29.98, and is indicated by the blue line on the diagram.
The positions of the above-mentioned signal-stations and the tracks of these seven vessels are all indicated in red on the accompanying Track Chart. This diagram should therefore be studied in connection with the chart, in order to form a clear idea of the general eastward movement of the trough of low barometer, and the accompanying rapid deepening of the depression upon reaching the coast.
THE SURVEY OF THE COAST.
BY HERBERT G. OGDEN.
At the inception of the Coast and Geodetic Survey in the early years of the century, so little was known of the dangers attending navigation along our extensive seaboard, that those who engaged in commercial enterprises were constrained to rely upon local knowledge and the reports of the hardy navigators who might carry their ventures to success. The charts available were by no means a sure reliance, and it has since been shown, contained many serious errors. The great headlands and outlying shoals that present the greatest obstacles to the safety of coastwise navigation, had not been carefully surveyed, and their relative positions to one another were only approximately determined.
The capacities of the harbors had not been ascertained, many were unknown; and even at the great port of New York, the Gedney or Main channel, was not developed until after the permanent establishment of the Survey in 1832, and the thorough exploration of the entrance was undertaken. A list of the sunken dangers and new channels that have been discovered during the progress of the work would fill pages. It is true such developments were to be expected in making a precise survey of the comparatively uncharted coast; but they, nevertheless, clearly point to the necessity of the work. We may also assume that the men who were controlling the destinies of the republic, realized that a knowledge of the coast was essential if they would succeed in building up a commerce, without which it was believed the prosperity of the people could not be assured. The deep draught vessels of the present day could not have traded along our shores on any margin of safety with the little that was known, and it is largely due to the perfect charting of the coast, that commercial enterprise has found it practicable to build the larger vessels of modern type to meet the increasing demands of trade.
The survey proposed was also required in providing for the public defence; as it is a self-evident proposition, that if we would protect a harbor from a hostile fleet, we must know not only the channels by which the fleet might enter, but their relations to each other and the points of vantage that should be utilized in obstructing them; and in modern warfare to know these things only approximately will not suffice, for precision is practiced now in the art of war, as well as in the arts of peace.
The lack of charts of our extensive Coast line, or indeed, of any practical information that could be utilized in a systematic defence against foreign aggression, was only one of the many perplexities that surrounded our forefathers in building the nation. By their valor they had wrested a jewel from the British Crown, and had inaugurated a system of government by the people, which on their sacred honors they had sworn to defend. But not a generation had passed away when they saw new dangers, and were forced to contemplate again taking up arms in defence of their rights. The land was theirs, even far towards the setting sun, pioneers had explored it, and they knew whence might come a hostile foe. But of the waters from far away to the eastward, that flowed on until they washed every shore and filled the great Bays, even to the heart of the Republic, they knew little, save that over that almost immeasurable expanse might come the fleet of destroyers to penetrate they knew not where, and inflict incalculable damage months ere the dreary tales might be told. It must be remembered there were no telegraphs, no railroads, no steamboats, in those days, and time taken by the forelock was time gained. The speed of man could not be overtaken as we see it to-day in the wondrous inventions of the last generations. Each community was dependent upon itself, alone, in time of danger, to ward off the blow or yield to a more powerful foe; assistance could hardly be obtained in months and perhaps not then. It was not possible for any man to study or to learn the points of danger, and prepare a system of defence.