Again, in 1843, and for the last time, the survey was the subject of legislative action. On the 3d of March of that year a Board was appointed by Congress, with authority to reorganize the mode of executing the survey. The plan agreed upon by the Board and approved by the President reaffirmed the scientific methods adopted by Mr. Hassler, and defined with considerable detail the organization and order required to carry them out, and these prime features, confirmed by subsequent experience, are yet retained, except so far as they have been extended and improved by commercial or other public requirements.

Since the survey was first authorized, the seaboard of the United States has been more than quadrupled in extent by the acquisition of Florida and Texas, and of California, Oregon, and Alaska. It now stretches through 210 of latitude and 14° of longitude on the Atlantic; 50 of latitude and 160 of longitude on the Gulf of Mexico; and on the Pacific, exclusive of Alaska, through 163° of latitude and 7° of longitude.

SUPERINTENDENTS UNITED STATES COAST SURVEY.

Ferdinand R. Hassler, August, 1816, to April, 1818.
Ferdinand R. Hassler, August, 1832, to November, 1843.
Alexander D. Bache, December, 1843, to February, 1867.
Benjamin Peirce, February 26, 1867, to February, 17, 1874.
Carlile P. Patterson, February 17, 1874.

Professor Hassler died November 20, 1843; Professor Bache, Febru ary 17, 1867, and Professor Peirce resigned February 17, 1874.

The survey may be said to have commenced in 1832, and between that date and the close of 1843 the Fire Island base had been measured; a network of triangles, primary and secondary, had been extended over the coast from Point Judith to Cape Henlopen and the Chesapeake, and the topography and hydrography had made commendable advance within the same limits.

It was not, however, until 1844 that the magnitude and responsibili ties of the work were fully realized. In the year following the Atlantic and Gulf coasts were divided into sections, in each of which the different operations of the survey were carried on simultaneously. By this di. vision of the field, commerce and the interest of each part of the seaboard experienced the benefits of the survey at the earliest moment. A similar system was carried out on the Pacifie coast upon the acquisition of California in 1849. Step by step the organization was perfected; a more thorough system was introduced in the conduct of the field and office operations; a higher standard was established for the topographical surveys; a wider field opened to hydrographic research; and the supervision of the Superintendent was extended to every detail. While "the Coast Survey owes its present form and perhaps its existence to the zeal and scientific ability of the first Superintendent," the organization as it exists to-day, complete in every branch, is the creation of Alexan

der D. Bache. To his untiring energy, administrative qualities, and varied scientific attainments, the progress, value, and high character of the survey may be justly ascribed.

The survey being under the charge of the Secretary of the Treasury, the regulations for carrying out the organic law and all decisions in cases affecting the survey or its personnel, are made by him, in consultation with the Superintendent. The Secretary is also the medium of official correspondence with the other Departments and with Congress. Estimates in detail for the different expenses to be incurred in the prosecution of the work are annually submitted by the Superintendent for the approval of the Secretary, and by him included in the Treasury budget for the next fiscal year. Upon those estimates all appropriations for the survey are specifically made by Congress.

The staff of the survey is composed of the Superintendent and of assistants and subassistants, consisting, by law, of civilians, Army and Navy officers. A previous experience, obtained by years of service in a subordinate capacity, is an indispensable requisite, in conjunction with other qualifications, for an appointment as a civil assistant. After that promotion depends altogether upon efficiency, regardless of seniority or influence.

The Superintendent is the immediate head of the survey. He lays out the work to be executed during the season throughout the country; he assigns to each assistant an appropriate duty under written instructions, a definite field of labor, and a limited credit with the disbursing agent; he takes general supervision over all the operations of the office, as well as over the construction and comparison of the standard weights and measures; he inspects the parties in the field whenever practicable; and at the close of the year when the reports of the different parties are received, he carefully examines the results accomplished by each assistant, and from these and the office reports the annual report is compiled. Besides these administrative duties, the discussion of scientific questions connected with the various operations of the survey, and all special investigations and experiments required for additional data, are conducted under his direction, while, at the same time, he co-operates with other bureaus of the Government, in matters in which the special information and resources at his control would benefit the public service.

The details of the scientific methods employed are fully explained in the annual reports, and in the Professional Papers published under the authority of the survey. It is only necessary here to give the general order of the field operations: Reconnaissance, measurement of bases, triangulation, primary, secondary, and tertiary; astronomical observations for time, azimuth, and latitude; telegraphic determination of longitude; topography, determination of the magnetic elements and hydrography, in shore and off, including the exploration of the Gulf Stream,

the investigation of tides and of other questions of value to the navigator and to science.

The results of these extensive field operations are regularly forwarded to the office at Washington, and are there revised, combined, and reduced, and find their way to the public in the form of four classes of charts: Sailing charts, general coast charts, coast charts, and harbor charts.

Beside these direct results-and among these should be included the data for studying the various problems of defense, river and harbor improvements, light-houses, and other national and local objects depending on the topography of the immediate line of the coast, peculiarities of the tides and variation of the magnetic needle along the coast, with researches for the law of variation over the entire continent-the survey has made valuable additions to geodetic science, and by the measurement of arcs of meridian and parallel, completed and in progress, will contribute the proportion of data, due from America to Europe, for determining the dimensions and figure of the earth.

In 1872, upon the recommendation of the Superintendent Benjamin Peirce, Congress directed that the Coast Survey should make a geodetic connection between the Atlantic and Pacific coasts, and also ordered that it should supply triangulation points to any State which would provide for its own topographical and geological survey. The advantages to the General Government of an accurate map of a State are quite as great as to the State itself, and co-operation in its construction was considered, for this and other reasons, an almost imperative duty. The policy of Congress in supplying the frame-work of the survey, consisting of a net-work of triangles secured by measured bases, and the usual astronomical determinations, insures to a certain extent its accuracy; and that, eventually, when the different network shall be connected with each other and with the triangulation of the coast, they will together constitute one harmonious whole based on the same scientific methods and standard of execution.

CATALOGUE OF INSTRUMENTS, ETC., EXHIBITED BY UNITED STATES

COAST SURVEY.

The exhibition on the part of the survey of the coast includes characteristic specimens of the instruments and apparatus employed in the triangulation, astronomical, surveying, and hydrographical operations of the survey, with a view to illustrate the order, character, and precision of the field-work; secondly, the results of the field operations, and of the intermediate processes as embodied in 300 charts and preliminary sketches of the Atlantic, Gulf, and Pacific coasts of the United States, published for the benefit of commerce and navigation; and finally the annual reports, and other publications, in which the methods adopted in the field and in the office are discussed and published for the advancement of science.

With but few exceptions no instrument or apparatus will be exhibited or method referred to which is not, in whole or in part, of American construction or origin.

STANDARD WEIGHTS AND MEASURES OF THE UNITED STATES.

In correlation with the commercial objects of the survey, and of the standard character of the measurements to be made during its execution, the construction of the standard weights and measures is under charge of the Superintendent of the survey. These standards will be represented by a complete set of the measures of length and capacity and of the different established weights, both of the American and metric systems, and by the comparators and balances used in their construction.

• GEODESY.

1. Compensation base apparatus, 6 meters in length; composed of two bars, one of brass and the other of iron, firmly connected at one end and free at the other. The free ends are connected by a lever so related to the different expansions as to preserve one point at an invariable distance from the fixed end. The specialties of the apparatus consist in the relative proportion of the cross-sections of the two bars, so that their acquired temperature will be equal during changes; in the delicate knife-edge lever of compensation attached to the free ends, and, at the fixed end, in the level contact so adapted as to admit of its use on inclined grades.

The apparatus was designed in 1845 by A. D. Bache, superintendent, and constructed in 1846 by William Wurdeman, mechanician of the survey, to whom many of the details are due. The equipment for the field includes a 6-meter standard bar arranged for comparison with the base bars, and a Saxton pyrometer mirror-comparator for indicating minute differences of length. These comparisons are made before and after the base measurement.

For a full description of the apparatus, its theory, practical working, and results, see Appendices 21 and 12, Reports for 1865 and 1873.

2. Models of the usual form of signal and of two or three varieties of the braced tripod and outside scaffold on which the instrument and observer are mounted to obtain elevation. Their height varies from 15 to 60 feet.

3. Heliotropes or signals for the longer lines of the triangulation, constructed on different plans, looking to certainty of direction, simplicity of adjustment, and economy in their cost.

4. Theodolite for primary triangulation; graduated circle 20 inches in diameter, with three micrometer microscopes reading to parts of a second by radial illumination; focal length of telescope 42 inches, and diameter of aperture 3 inches.

Constructed for the Coast Survey by William Wurdeman.

5. Theodolite, repeating, for secondary triangulation; graduated circle, 12 inches in diameter, reading to three seconds by means of verniers and microscopes. Circle by Gambey, of Paris; upper parts, including telescope of 26 inches focal length and 23 inches aperture. Made at Coast Survey Office.

6. Theodolite, repeating, for tertiary triangulation, diameter of circle, 10 inches. Made by C. Fauth, of Washington.

7. Vertical circle, repeating, for measuring double zenith distances; circle by Gambey, 12 inches in diameter, with four microscopes and verniers reading to three seconds. Movements reconstructed at Coast Survey Office.

8. Zenith telescope; focal length, 48 inches; diameter of aperture, 3 inches; constructed at Washington by William Wurdeman, and used for determining the latitude of a station by measuring the difference in the meridional zenith distance of two stars of about the same altitude and culminating at nearly the same time, one north and the other south. of the zenith. The distinctive features of the instrument are the filarmicrometer eye-piece and delicate spirit level, and of the method, its simplicity and freedom from errors of refraction and personal equation. (For details see Appendix 10, Report for 1866.)

The above method of employing the zenith telescope originated with Capt. Andrew Talcott, United States Engineer Corps, in 1834. The instrument was introduced in the survey in 1846, and having received several improvements suggested by experience, it has been exclusively employed in the field-work since 1851.

9. Transit and equal-altitude instrument, or a combination of the zenith telescope and portable astronomical transit, by adding to the latter a filar-micrometer eye-piece and delicate level, and by dividing the iron horizontal frame into two parts, so that the upper part, carrying the entire instrument, can be revolved 180° or more in azimuth, without disturbing the level or interfering with its relation to the telescope. (See Appendix 8, Report for 1867.)

The combination was first suggested by Assistant George Davidson in 1853, but it was not until 1868 that the instrument, as exhibited and now used in the survey, was perfected and constructed at the office.

10. Astronomical transit, with reversing apparatus; focal length of telescope 46 inches, and diameter of aperture 22 inches; twenty-five threads divided into five groups, together with battery, a Bond astronomical clock, or chronometer, with break-circuit attachment, chronograph, keys for tapping, and the usual equipment for determining differences of longitude by the electric telegraph method, purely American. (For details see reports and scientific papers of the Survey and Astronomische Nachrichten, Nos. 632 and 666.) The theory and details of the method were elaborated by Assistant Sears C. Walker in 1845, were practically carried out in 1846, and by means of the circuit-breaker and revolving-cylinder chronograph designed by Joseph Saxton, United