REPORT ON THE COAST SURVEY

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EXPLORATION OF THE GULF STREAM.— A hydrographic survey of our coast would be incomplete, if it did not embrace the investigation of the remarkable ocean current which divides the waters adjacent to our Atlantic coast from the wide ocean beyond. The importance of its explanation is recognized in the original law of 1807, by extending the scope of the survey so as to embrace it. On assuming charge of the work, Prof. Bache at once organized a system of observations for the purpose of determining its limits and principal characteristics.

Previous to that time, casual observations had been made by private and public vessels of England and America, the results of which were collected by Major James Rennell, F.R.S., and published in his work on the currents of the Atlantic ocean. These observations were confined to the surface, and gave only vague results.
The method of exploration adopted by Professor Bache was, to determine the limits of the stream by the temperature of its waters at all depths, by means of deep sea thermometers, along lines perpendicular to its several directions. This work was commenced in 1845, and has been continued up to the present time. Sixteen sections have been run across the stream at different points of the coast, along which the temperature of the water at various depths has been determined, and also sections of the bottom, wherever it has been found possible to obtain soundings.

For these explorations thermometers are required specially adapted to the purpose. Ordinary thermometers would indeed suffice for observing the temperature of the surface, but in order to obtain that prevailing at some depth it is necessary that they should be self-registering, and able to withstand the crushing pressure of the water. They must be of simple construction, not liable to derangement by ordinary shocks, nor affected in their indications by the enormous pressure to which they are exposed; they must readily acquire the temperature of the water, which should have free access to all parts, and they must therefore be made of materials not liable to corrosion by salt water. After many experiments on a variety of instruments, as Rutherford’s, Sixe’s, Breguet’s, and Jurgensen’s, the metallic self-registering thermometers invented by Saxton, the assistant of Prof. Bache in the office of weights and measures, was found best to fulfil the above conditions, and it has superseded all others in use. The statistical table shows that over 3400 cast have been made and registered for depth and temperature of the Gulf-stream. The results arrived at from the discussion of these observations will find mention in the second part of this report.

The work is still in active progress; and it is much to be desired that the exploration eastward from the American side of the northern part of the stream, should be met by a corresponding exploration from the shores of Great Britain westward, which would complete our knowledge of the Gulfstream, throughout its whole extent from the shores of Florida to those of Ireland.

OFFICE-WORK AND PUBLICATION OF CHARTS.— The results of the field-work are prepared for publication at the office of the Coast Survey, in Washington City. The reductions of geodetic and astronomical observations are, in the first instance, made by the observers themselves; but a second computation is independently made in the computing division of the office by persons having no connection with the field-work. Strict scrutiny of the observations, and perfect security against errors of computation, are thus insured; the two computations being examined and compared by an experienced person, who refers whatever discrepancies may appear to exist to the Superintendent.

Of the formula and methods employed in the computation, not even a sketch can be given in a general review like the present. It will be sufficient to state that in this, the purely mathematical part of the operations, as marked improvements have been made as in any other branch of the work. The processes are highly systematized, and partake of the highest refinements of modern science, as is evidenced by the systematic application of the method of least squares in the discussion and adjustment of results.

The construction of the maps and charts for publication commences in the drawing division of the Coast Survey office.

The projections of the meridians and parallels are made according to the system of polyconic development of the earth’s surface, of which special accounts, with accompanying tables, may be found in the C.S. reports for 1853 and ‘56. On these projections, the positions of the triangulation points are laid down according to their latitudes and longitudes, obtained by the geodetic operations. On the sheets covered by the topographical and hydrographical surveys, the triangulation points are likewise laid down, with reference to similar projection lines, and the reductions to the scales of publication are thus made with extreme accuracy by indefinitely projecting the controlling points o the survey, and drawing in the details by means of small squares, or by the pantograph. The camera lucida has sometimes been employed, but is found too trying to the eyes of draughtsmen. It may be mentioned here that experiments are in progress having in view the application of photography to the reduction of the maps, and that there is good reason to hope for successful results.

The maps and charts emanating from the Coast Survey are divided into two general classes– viz.: preliminary or provisional charts and sketches, issued with as much expedition, after the individual surveys, as is consistent with accuracy of general portraiture, and designed to supply the more immediate and pressing demands of commerce; and the finished charts proper, which must embody all the information furnished by the survey, even of the minutest detail, and which ought at the same time to be executed in the style of the highest existing artistic excellence.

The charts are various in character, according to the immediate objects which they are designed to subserve. Thus, one description of chart has for its use to convey to the navigator a just notion of an extended coast line, and of the relative positions of objects most conspicuous at a distance, so as to enable him to identify his position as he approaches from the open sea. Another gives him the minuter information which he needs when the purposes of his voyage bring him for any reason closer in-shore. They are, therefore, classified under the three heads of general coast charts, coast charts, and charts of harbors, anchorages, &c.

The general coast (or offshore) charts, on the scale of 1/400000, represent the shore-line of the coast and its general topographical features, so as to be readily recognized by the navigator approaching it. Ommitting minute details, they show at a glance the contour of the shore, the location of the islands, shoals, and rocks which the navigator may encounter in approaching the main land; the soundings off-shore, selected in-shore soundings, and finally the principal natural and artificial landmarks.

The coast (or in-shore) charts, on the scale of 1/80000, and the harbor charts, on various scales, from 1/5000 to 1/80000, present with minute accuracy every natural feature or other object above or beneath the water which can be introduced without producing confusion or indistinctness. In these charts, the hydrography is so elaborately displayed as to indicate, by the shades of depth, the fathom lines and the soundings, the safe route for a vessel of any given draught, and, as a necessary consequence, to exhibit, at sight, the principal channels by which every important place may be approached. The lines of range of natural landmarks, or of lights and beacons, the appearances of different light-hosues and the characters of their lights, with all other indications by which cahnnels are signalized to the mariner, are also everywhere given in the fullest manner. They further contain sailing diretions designed to furnish information in entering harbors, graphic views of important landmarks, and sketches of the position and characteristics of light-houses, beacons, and buoys– such as may serve to assure the navigator of his true position, whenever any of these objects are in sight. The topograhpy of the shore and of the land for some distance from the shore is furthermore minutely given, for various reasons, some of which have been hinted at, and of which others will be alluded to hereafter.

Of the general coast charts (1/400000), it is estimated that the Atlantic and Gulf coasts will be covered by sixteen sheets.

The scheme of coast charts (1/80000), planned for these portions of the coast, embraces one hundred and thirteen sheets.

The Pacific coast is as yet too little known in its minute features to afford a basis for a definite estimate.

Besides these finished charts, which, from their nature, require a lengthened period for the collection of the data from which they are compiled, and are also slow of execution,– their elaborate details requiring the highest skill in drawing and engraving,– there is issued a series of preliminary charts and hydrographic sketches. These, embodying information which it is desirable to make accessible at the earliest available opportunity, are prepared and published as soon as possible after the completion of the work in the field. For the principal charts of this latter class, the scale of 1/200000 has been adopted; they are less elaborately finished than those before described, and are designed to meet the wants of the public, until the more perfect maps can be made ready for issue. They also enable the office department of the survey to keep up with the operations in the field and float, each season’s work as it is turned into the office being drawn and engraved on the plate, and, when required, a new plate is made by the electrotype process, large enough to retain the old and receive the new work. Of the preliminary sea-coast charts, it is estimated that the Atlantic and Gulf coasts will require thirty-three sheets.

When the charts are drawn and verified, they pass into the engraving division of the office, where they are executed on copper by a corps of engravers, among whom there are some artists of distinguished merit. Here, as in every other department of the work, the division of labor is productive of economy in time, combined with superior excellence of results. The engraving of outlines, of hill-topography, of the dotted shading of the sea-bottom, of the figures denoting the soundings, and, finally, of the lettering, are so many different branches of the art, executed by different persons, who have, by talent or practice, acquired superior skill. When the plates are completed, copies are taken of them by the electrotype process, which are used for printing the charts, while the original plates are preserved among the archives.

The electrotyping establishment of the Coast Survey is very extensive, and one of the most successful in the world. It was in practical operation several years before the process came into general use, and considerable advances were made in the art at this establishment. The method of iodizing the matrix, which effectually prevents adhesion without interfering in the least degree with the perfect sharpness of the cast, was then discovered, and, by an admirable system of experiments, the best size and arrangement of batteries, the proper temperature of the solutions, and all other conditions necessary to produce the best, most uniform, and cheapest results, were developed. The practical use of the process is not confined to the production of copies for printing. The division of labor in engraving the charts is often very much facilitated, and great despatch in their production is attained, by dividing, and executing them in two, or even four separate pieces, which are afterwards joined on a common electrotype plate.

The charts are finally printed at the Coast Survey office, and distributed to sales agents in the principal seaports. The prices are fixed at very low rates, varying from fifteen to seventy-five cents per sheet, so as to place a complete set of sheets within the reach of every navigator. Copies are also freely distributed to seminaries of learning, public libraries, and other institutions of a similar character.

PUBLICATIONS OF OBSERVATIONS AND METHODS.– The importance of an early publication o the observations made in the progress of the Coast Survey, and of the methods practised in the execution and computation of the work, was repeatedly urged upon Congress by the Superintendent, and means were appropriated towards that object in 1854–55, and in the two subsequent years. It has been the reproach of works of this kind, that the results only are furnished, while the data from which they are derived are not presented for scrutiny at all, or if at all, so late that for practical use they have lost much of their value. The publication of the archives, while it secures the work against loss by accident, and submits it to the criticism of the world, has the further great advantage, that it insures the full information from, and responsibility of, those by whom the work is executed.

Considerable progress has been made in this work, as appears from the account given in the annual report of the Superintendent for 1856 and 1857, where also the plan of publication is developed, of which a brief sketch must suffice here. The order of arrangement for the geodetic work is at first necessarily chronological, the volumes for each year comprising the records and results of all the various classes of work; while after the completion of the survey the volumes would most naturally arrange themselves according to the different operations. With this end in view, the plan has been carefully laid out so that the matte contained in the annual volumes may ultimately be divided, and rearranged so as to form volumes relating to separate subjects. The record of the observations is given in full, and being unchangeable, is kept separate from their reduction, of which the principal steps are given, and which may be liable to change from accumulation of data or from improvement of methods. As far as practicable the record and reduction of the observations are arranged on opposite pages. The volumes thus in course of preparation embrace, besides other subjects, the operations of Geodesy, Chronometric Longitudes, Telegraphic Longitudes, Explorations of the Gulfstream, and Sailing Directions. It will be remembered, that, in addition to the great variety of interesting communications on subjects connected with the Coast Survey made by Prof. Bache, it was the exhibition of a volume of proof-sheets of the geodetic volume to the members of the Association at the Montreal meeting which led to the appointment of the present Committee, who can only express their deep regret on learning that the publication of the work has been unavoidably suspended for want of the necessary appropriation to carry it forward, and their earnest hope that, when the temporary embarrassment of the public treasury is relieved, the means will be supplied for its speedy consummation. The publication of the observations and methods will be hailed with great satisfaction by the men of science at home and abroad, while the volumes relating to the harbors and coast will have nearly the same interest for commercial men and navigators.

ORGANIZATION AND ECONOMICAL MANAGEMENT OF THE COAST SURVEY.– The whole work is under the administrative direction of the U.S. Treasury Department. The Superintendent arranges the plan of conducting the work, and issues instructions for its execution to his assistants; he directs and is responsible for the accuracy of all the scientific parts of the work, and controls the expenditures, making an administrative examination of the accounts, which is a great source of economy. Besides performing these duties of superintendence, he engages personally in observations in the field, and in those able discussions of the results of which the pages of our scientific journals contain ample evidence.

The corps of assistants is composed of three classes,— civilians, officers of the army, and officers of the navy. The civilians, many of whom have been trained in the Survey, entering as cadets, or aids, as they are designated, and rising by merit to higher grades, form a nucleus of a more permanent kind. The officers of the Army and Navy are detailed by the heads of their respective Departments, on application of the superintendent; they are liable to be changed frequently, as the exigencies of the military or naval service require. Receiving no extra emolument for their services on the Coast Survey, their positions are only valuable to them under peculiar circumstances, which change frequently, and there is a limit, therefore, to the calls upon them for service. Without the nucleus of civilians the whole work might be disorganized by calls for the services of the Army and Navy officers in their immediate professional line. On the breaking out of the war with Mexico, all the officers of the line of the Army, and part of those of the staff, serving on the Coast Survey, were detached from it. The harmonious cooperation of these three classes of persons which has been maintained during the past fourteen years is highly advantageous to the country, and could not, it is obvious, be secured except under the direction of a distinguished civilian; sine questions of rank and authority between officers of the different branches of the service would inevitably interfere disastrously to the best interests of the work, if its direction were confided to either the War or Navy Department; and if the operations on land and at sea were carried on under distinct organizations, then would result a want of cooperation as to time, methods and objects, by which the hydrographic survey would fail in a great measure to derive from the land-work those elements of accuracy which are essential to its perfection.

The progress of the Coast Survey, form year to year, is communicated to Congress in the annual reports of the Superintendent. Besides an account of the extension of the work in the different sections, accompanied by sketch-maps illustrating the same, these reports contain, as an appendix, the preliminary maps, charts and sketches produced during the year, and valuable contributions to knowledge in the form of scientific discussions of various subjects connected with the survey, such as tides and terrestrial magnetism, and of new methods of observation or computation developed by the persons engaged in the work. The high character for interest and usefulness which these reports sustain is too well known and universally acknowledge, to require commendation. With wise liberality Congress has printed large editions of these for general diffusion, and the distribution list shows that they are in great demand not only on the seaboard, but also in the interior states, evincing the gratifying fact that large numbers of citizens other than those immediately engaged in commerce and navigation feel an appreciative interest in a work designed for the benefit of the whole nation.

It may not be inappropriate in the general sketch which we are taking of the actual operations of the Coast Survey, to observe that the economy which has marked the conduct of this national work has been no less remarkable than the comprehensiveness of its scope, the rapidity of its execution, the scientific exactness of its processes, or the substantial value of its results. It may very safely be said that no other government has hitherto succeeded in securing, in this branch of its service, results so large and so valuable in so little time, and at so little expense. This fact is no doubt in a great measure due to the wisdom with which the work has been laid out, to the administrative ability which has secured activity and efficiency in all its departments, to the division of labor, and to the personal ability or skill, as well of the subordinate members of the corps, as of the chief. But it is also, and in no less measure, due to the system of disbursement and financial control, and to the method of keeping the accounts, introduced by the present Superintendent, which are judiciously devised so as to protect, in the most effectual manner, the public interests.

A careful study of the question of relative progress and expenditure, and comparison of the cost of our national survey with that of the surveys of other nations, for which the data are given in a special report prepared by the Superintendent in 1857, in compliance with a call from the Treasury Department, have led the Committee to the conclusion expressed at the close of this report in regard to the economy of the present system. The details are of a character which would extend this repot to an undue length, but the Committee may express their desire that the document referred to be made accessible to the public through its publication by government.

PART II:— RESULTS.

THEIR BEARINGS UPON THE NATIONAL WELFARE, AND UPON THE ADVANCEMENT OF SCIENCE.

In passing to considering the results actually wrought out in the progress of the survey of our coast, and the various important bearings of these, both useful and scientific, the Committee are aware that it is difficult to avoid the appearance of occasional repetition: since any sketch, however cursory, of the history of the work, or any description, however imperfect, of the processes employed in its execution, must, from the nature of the case, be in itself, to some extent, an anticipation of the results; though these be mentioned only by way of allusion, or introduced purely for the sake of explanation, or of illustration. In so far, nevertheless, as may be practicable, care will be taken not to retreat ground already beaten.

The valuable results which the Coast Survey has been, and still continues to be, the means of securing, are distinguishable into two calsses, according as we restrict our view to the objects for the sake of which the Survey was expressly instituted, or extend it to those more varied interests which are incidentally, but no less positively, promoted by its operations.

For the sake of convenience, w will refer to these two classes of results under the heads, direct and collateral.

DIRECT RESULTS: – BENEFITS TO NAVIGATION AND COMMERCE

The direct results are the numerous and invaluable aids and benefits to navigation and commerce, which, being the ends most immediately and distinctly contemplated in the origination of the work, it is in the importance which attaches to them that the main argument in favor of its prosecution to completion must always be found.

We may indeed dwell with just and honorable pride upon the services rendered to science, in its various branches, through the instrumentality of a work which can only be prosecuted by the aid of recondite scientific principles, applied in practice by accomplished and zealous scientific men. As physicists, the members of this Association may even, perhaps, regard with higher satisfaction the contributions furnished to our knowledge of nature, the improvements originated for us in methods of observation, and in the ingenious mechanical contrivances invented for promoting instrumental accuracy, which we owe to the men engaged in this great public work, and, through them, to the work itself, than our tastes may incline us to feel in view of the more material and immediately tangible results which flow from it; but we must not forget that the majority of mankind look upon all undertakings which involve expenditure to the public from a utilitarian point of view; and while, therefore, we may justly challenge the admiration of all men, whether they be professedly scientific or not, for results which we ourselves so greatly prize, yet we must not expect that all men will so far enter into our enthusiasm as to undertake such works for the sake of such results only. In the present case, fortunately, the directly useful results accomplished are so palpably great, that it will be sufficient to name them, in order to satisfy the most exacting economist in regard to the wisdom of the outlay by which they have been secured.

We therefore present now a summary view of the progress already made towards the completion of the work, followed by a condensed table, compiled from data obtained from the Coast Survey office, showing, in two parallel columns the work executed previous to 1844, under the superintendence of Mr. Hassler, and that from 1844 to 1857, inclusive, under the superintendence of Professor Bache.

PROGRESS, OR PROPORTION OF THE WHOLE COAST SURVEYED.– The survey has been extended into every seaboard State and Territory of the United States, on the Atlantic, Gulf of Mexico and Pacific coasts, and is now in progress, either in field or office-work, in all of them.

For the purpose of estimating its progress towards completion, we may consider either the extent of general coast-line (omitting minute indentations), or the length of the shore, or water-line, including that of bays, sounds, islands and rivers, to be covered by the triangulation.
The general coast-line of the Atlantic (including Delaware and Chesapeake, as well as all open bays,) is estimated, form recent measurements, made on the progress sketches, in the office of the Survey, at 3,036 miles; that of the Gulf of Mexico, at 2,162 miles; and that of the Pacific (including the Straits of Fuca), at 1,866 miles: making, in all, 7,064 miles.

A measurement of the shore-line (including bays, sounds, islands and rivers,) covered by the triangulation, made in a similar manner, gives for that of the Atlantic coast, 14,723 miles; of the Gulf of Mexico, 10,406 miles; and of the Pacific coast, 4,252 miles: in all, 29,381 miles. Of this shore-line, the triangulation has already extended over, on the Atlantic coast, 10,787 miles; on the Gulf coast, 4,075 miles; and on the Pacific coast, 1,288 miles: in all, as appears in the table of statistics, 16,150 miles.

Each of these two modes of estimating the work already executed, and that remaining to be done, affords us this conclusion: that the Atlantic sections are nearly three-fourths done, and the Gulf sections one-third done.

Our knowledge of the minuter features of the Pacific coast being as yet in a much less advanced state than that of the other two portions of the coast, renders a precise estimate for it comparatively less practicable; as far, however, as we can venture to determine in this matter, the Pacific section is not quite one-fourth executed.

With the limitation just specified, taking the whole coast of the United States into consideration, the survey is carried forward about one-half to completion. This estimate is based on the triangulation executed; a similar consideration of the topography will lead us very nearly to the same conclusion.

The length of the general coast being taken, as above stated, it appears that the topography is executed over 1,889 miles in the Atlantic section, 764 miles in the Gulf section, and 259 miles in the Pacific section: in all, 2,912 miles, out of 7064 miles, showing two-fifths of the whole. It is to be borne in mind, in making this estimate, that the topography is, in general, a whole season behind the triangulation, and that the hydrography thereafter follows in its turn.

Looking at these data of the field-work, and adding to our view the office-work consequent thereon, we are justified in considering that, at the rate of appropriation for the three years from 1855 to ‘58, and with the like efficient management, the survey of the Atlantic and Gulf coasts may certainly be essentially completed in from twelve to fifteen years. This agrees substantially with the latest estimates of the superintendent of the work.

Estimates of time for completion were, in the early stages of the survey, necessarily but conjectural, on account of the inaccuracy and looseness of the geographical maps of the coast, then extant, the length of shore-line shown on them being greatly in defect; but, as data for a more and more close approximation to the true amount have become available by the operations of the survey itself, our information on this subject is now so much more detailed and reliable, that we may look wit ha tolerable degree of confidence on the conclusion to which we have arrived.
Extent of connected triangulation, and localities where the survey is yet incomplete.— The triangulation is continuous from Mount Desert, in Maine, to Shallotte inlet, south of Cape Fear, in North Carolina, stretching over more than ten degrees of latitude, and as many of longitude, including the coast of ten States, and the greater part of the coast of two others. Then, with an interval of about seventy miles, it extends along the coast of South Carolina and Georgia, with two gaps, to the Ossabaw entrance. It covers, on the coast of Georgia, Sapalo entrance, St. Simon’s sound and Brunswick harbor, St. Mary’s, Georgia, and Fernandina harbor and St. John’s river, Florida. It is continuous from Cape Florida to the Marquesas, west of Key West, completing the connection of the outer keys and reefs of South Florida. On the western coast of Florida, after a gap from Cape Sable to Crystal river, it extends to beyond Cedar Keys; over Ocilla river entrance; St. Mark’s harbor; from East Pass through St. George’s and St. Vincent’s sounds, including Apalachicola harbor; St. Andrew’s bay and Pensacola harbor and approaches. On the coast of Alabama and Mississippi sound and part of Lake Ponchartrain, connecting Mobile and New Orleans. On the coast of Louisiana, it covers Chandeleur sound to Isle au Breton sound; part of the Delta of the Mississippi; Isle Derniere and Caillou bay; Atchafalaya and part of Cote Blanche bays. On the coast of Texas, it extends over Galveston entrance, the shores of East and West bays, and the coast as far as Matagorda bay, inclusive, and is commenced at the Rio Grande, and is being prosecuted northward.

On the coast of California the main triangulation is complete from north of Sonora mountain to south of Monterey bay, and the secondary triangulation, connected with this along the coast-line, is nearly completed. Secondary triangulation has been executed at San Diego, near San Pedro along the Santa Barbara coast, and on the Santa Barbara Islands; in San Francisco, San Pablo, Suisun, Ballenas, Drake’s and Tomalas bays. The river entrances of the coast of Oregon have been surveyed, and Columbia river triangulated up as far as Astoria. On the coast of Washington Territory, the triangulation has extended over Shoalwater bay, Washington sound, Admiralty inlet and parts of Puget’s sound, and Hood’s Canal.

On all portions of the coast where the scheme of the main triangulation did not afford the requisite facilities for immediate progress, preliminary triangulations have been executed in advance, to serve as a basis for the detailed work, and to be verified in turn.

Directly on the foregoing triangulation, the topography has followed with, generally, but one season’s interval, and, taking hold of the determinations made by both these series of operations, the hydrography has proceeded to take its part in the combined work.

It may be here remarked that the proportion of the amount of topography to that of the other parts of the work has been, since 1844, diminished purposely, it is not being carried so far inland, partly in consequence of the objections urged, in the discussions in Congress, to the extent of topographical detail carried out in the earlier stages of the work, and partly owing to the different character of the southern coast, where the larger proportion of the recent work has been carried on.

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