States Coast Survey, were brought to their present degree of perfection in 1849. 11. Personal error apparatus, portable, to enable the assistant on telegraph longitude duty to determine the error he may have committed, if any, in noting the time of the star transits, in consequence of some personal peculiarity, temporary or permanent. The clock-breaks and apparatus-breaks are in one electric circuit, the registration being automatic, while the breaks for the apparent transit by the observer are effected through a second circuit, the true and observed time being thus recorded on the same chronograph sheet, side by side. 12. Personal equation apparatus, portable, constructed on the same general plan as the preceding. The improvements consist in the delicate arrangements for adjusting the electric-break to the bisection of the star by each of the five threads, and in the addition of a telescope of minor power to aid in making an accurate adjustment of the apparatus-breaks. The five lines and the image of the artificial star appear upon the same surface; there is, therefore, no parallax; hence two or more observers can obtain their personal equation by observing at the same time through small telescopes or field-glasses at a suitable distance. (For description of details see Appendix, Report for 1875.) Designed and constructed by Werner Suess, mechanician, United States Coast Survey. 13. Mercurial horizon, designed by J. H. Lane, Coast Survey Office, to extinguish ripples or oscillation, in the mercury. SURVEYING. 14. Plane-table, with alidade, magnetic declination needle and telemeter, as improved from time to time in its adjustments, stability, and usefulness; constructed at the office and used in the survey for topographical details. (See Appendix 22, Report for 1865.) 15. Gradienter. 16. Magnetic apparatus for determining the declination, dip, and intensity of the magnetic force. Magnetometer No. 7 is for observing work requiring precision and facility for observing large disturbances, and is of the construction which, in deflection, keeps the magnets at right angles to each other; a simple contrivance has been added for determining the induction co-efficient. For ordinary field-work the survey uses the theodolite separate from the box containing the magnet, although both are mounted on the same stand. In this case the deflecting magnet remains in the plane of the magnetic prime-vertical. The principle of collimation is employed in both forms. 17. Dip circle No. 10, of the ordinary pattern, with the single improvement that the needles have movable axles, admitting of different positions to eliminate the defects in the shape of the pivots. (See Appendix No. 14, 1872.) Made at Washington by William Wurdeman. HYDROGRAPHY. 18. Model of hydrographic signal; shape pyramidal, base triangular, made of rough scantling, boarded up on one or more sides and surmounted by a staff bearing a distinctive flag. The color of the boarding and flag is either white or black, to suit the background. Height varies from 15 to 40 feet. 19. Hydrographic sextant, used for measuring the angles required to determine the position of the sounding boat. Made by E. Lorieux, père, Paris. 20. Three-arm protractor for plotting on the chart the position of the sounding boat. Made at United States Coast Survey Office. 21. Deep-sea sounding machine for wire, constructed from the original plans of Sir William Thomson, with the addition of an accumulator worked by coil springs. By means of the accumulator and its arrangements, the exact amount of wire paid out is registered; a strain can be put on the friction line attached to the reel at the instant the sinker strikes the bottom; and, in reeling in, the sudden strain brought on the wire by the rolling and pitching of the ship can be eased. Made at the office from the designs of C. D. Sigsbee, lieutenant-commander, U. S. N., and assistant, United States Coast Survey. 22. Sounding-rod and deiacher or a single rod to serve either for using and recovering a light sinker, or of detaching, with increased certainty, a heavy lead. The apparatus secures a large specimen of the bottom. Made at office from designs of C. D. Sigsbee, lieutenant-commander, U. S. N. 23. Water specimen cup so constructed that it can be attached to any part of the sounding line as it is paid out, and detached as it is reeled in without materially affecting the opening or closing of the valves of the cups then under water. Specimens of the water can be thus obtained, at a single cast, from as many depths as there are cups employed. Made at office from designs of C. D. Sigsbee, lieutenant-commander, U.S. N. 24. Specimen cups, several varieties, shipped in the lower end of a deep-sea lead to bring up specimens of the bottom. Designed by Lieutenant (now Rear-Admiral) B. F. Sands, Lieut. H. S. Stellwagen, and Acting Master R. Platt, U. S. N., while serving as assistants in the survey. 25. Detaching sinker, water-bottle, and specimen cup: two varieties. Designed by Admiral D. D. Porter, U. S. N., and G. R. Wilson, of Washington. 26. Massey's sounding indicator. 27. The Miller-Casella maximum and minimum thermometer for deepsea temperatures. 28. The Negretti-Zambra deep-sea thermometer. The three preceding instruments are of British origin and make and are used in the Coast Survey as giving the most satisfactory results. 29. Hydrometer, with can and attached thermometer, for sea-water. Designed by J. E. Hilgard, United States Coast Survey. 30. Self-registering tide-gauge, as at present used in the survey. The record is made on a large horizontal cylinder driven by a balance-clock of peculiar construction. So soon as the paper is covered with curves made by the rising and falling of the float, the cylinder is taken out and another substituted. The first cylinder is then put into the readingbox, and the height of high and low water, and heights at every hour, are read off on a scale of equal parts and tabulated. For details see Directions for making tidal observations. Constructed at the office from designs by R. S. Avery, United States Coast Survey. 31. Dredge for obtaining specimens of the bottom and of deep-sea fauna. OFFICE AND PUBLICATIONS. 32. Record books ruled and of uniform size and color for each class of field-work and blank forms for computations, adopted in the Survey to secure system in the field and order in the archives. 33. Chart showing the character of the principal triangulation of the Coast Survey. 34. Chart of the isogonic lines, or the declination of the magnetic needle in the United States. 35. Portfolio containing twenty characteristic specimens of the sailing charts and general charts of the coast, drawn, engraved, and published at the office of the Coast Survey. 36. Portfolio containing forty-five similar specimens of coast charts. 37. Portfolio containing forty similar specimens of harbor charts. 38. Electrotype plates, alto and basso, 35 by 42 inches. (New York entrance.) 39. Steel-faced plate (Mount Desert Island). Deposit of iron is made upon this engraved copper plate by the galvanic battery from a solution of ferrous sulphate and ammonic chloride. The electrotype iron is very hard and retains magnetism permanently. Thickness of deposit, 0.035 millimeter, or about 7 of an inch. Number of impressions unlimited, since deposit can be renewed at pleasure. 40. Annual reports of the Superintendent. 41. Professional and scientific papers relating to geodesy, astronomy, methods of determining differences of longitude, surveying, hydrography, terrestrial magnetism, tides, the Gulf Stream, and other kindred subjects connected with the various operations of the survey, including Coast Pilots and Tide Tables. STANDARD WEIGHTS AND MEASURES. 42. American standards of length, weight, and capacity. 43. Metric standards of length, weight, and capacity. 44. Invariable meter compensated for temperature; designed by Saxton. 45. Mirror comparator for end-measures (Saxton's pyrometer). 46. Vertical contact level comparator; designed by Hilgard. 47. Optical comparator for comparing line-measures with end-measures; designed by Hilgard and Lane. 5 48. Balance for 1 pound, sensible to of a grain; designed and constructed by Hassler, with improvements by Saxton. 49. Balance for 25 pounds, sensible to one tenth of a grain with that load; designed and constructed by Saxton. |