True Apparent Places of Thirty-seven of the Principal Fixed Stars for every tenth day of the year. Jan. 1 20 7.99 5 17.1 27 53.98 40 33.4 31 47.68 38 53.4 17 51.4149 11.5 43 23.36 28 31.7 11 8.28 17.7 54.17 31.2 47.79 50.251.51 9.9 23.42 30.1 51.64 8.4 23.52 28.2 26.7 25.3 31 11.93 27.7 June10 12.01 28.1 20 July 10 12.03 20 11.96 29.2 30 11.85 29.3 57.59 31.6 57.71 33.5 51.81 51.3 12.05 28.4 57.79 35.4 51.94 54.3 55.25 14.8 30 12.06 28.7 57.83 37.2 52.02 57.3 55.40 16.4 29.0 57.84 38.9 52.05 39 0.2 55.51 18.0 27.39 38.3 57.81 40.4 52.03 3.0 55.58 19.4 27.48 40.1 57.74 41.7 51.96 5.5 51.64 48.3 54.85 True Apparent Places of Thirty-seven of the Principal Fixed Stars for every tenth day of the year. Epoch. - The Upper Culmination at Greenwich. h. 21 8. h. 21 i m. 8. 30 22 8. m. Jan. 1 36 15.5944 47.2 14 56.7957 4.9 58 0.37 3 3.4 49 16.29 25 24.1 57 13.8023 42.2 Dec. South. Right Asc. Dec. South. Right Asc. Dec. North. Dr. Young's Refractions, the Barometer being at 30 inches, and the internal Thermometer at 50, or the external at 47 degrees; with the Corrections for + one inch in the Barometer, and for one degree in the Thermometer of Fahrenheit. From page 19 of Vol. I. of Pearson's Practical Astronomy. Table of Refractions, continued. App. Alt. Refr. B. 30, Diff. for +1 Diff. for 10 App. Alt. Diff. for +1 Diff. for 10 App. Alt. Diff. for +1 Diff. for 10 The correction for an increase of altitude of one inch in the barometer, or for a depression of one degree in the thermometer, is to be added to the tabular refraction; but when the barometer is lower than 30 inches, or the thermometer higher than 47 degrees, the correction becomes subtractive. When great accuracy is required, 0.003 inch should be deducted from the observed height of the barometer for each degree that the thermometer near it is above 50 degrees, and the same quantity added for an equal depression. Logarithm for converting Sidereal into Mean Solar Time +9.9988126. 66 Mean Solar into Sidereal Time + 0.0011874. 66 66 A second of time at the Equator contains 1521 feet. THE COAST SURVEY OF THE UNITED STATES. By Lieut. C. H. Davis, U. S. N. Ir was to be expected that a people devoted to the pursuits of commerce, and depending, in some degree, on the sea as a means of communication between distant parts of the national territory, should demand, at an early period of their history, a competent survey of their coasts and inland waters. But a short time previous to the separation of the Colonies, charts had been constructed of the shores and harbours of North America, under the direction of F. W. Des Barres, his Majesty's Surveyor-General for the Colonies. The progress of his labors was interrupted by the Revolution. The surveys made under the personal superintendence of Des Barres still bear testimony to his skill and fidelity, and present a generally correct view of those parts of New England and the British possessions which, being rocky, are but little liable to change. They continue to form the principal basis of the charts of the northeastern coast of this continent. In the Southern and Middle States, however, they have been rendered worse than useless, by the inconstant character of the bottoms, and the unequal merit of the originals. The surveys of Des Barres, covering a vast extent of coast, were originally deficient in minuteness of detail, and in hydrographical information; and these defects have been increased by the rapid and extensive changes in the direction, means, and wants of navigation caused by the growth of the country. The project of a complete survey, conducted upon a uniform system and extending over the whole coast, was first proposed by the late Professor Patterson, in 1806. It combined three objects, the astronomical determination of prominent points, a triangulation to connect those points, and a hydrographic survey based upon this triangulation. Mr. Gallatin, then Secretary of the Treasury, encouraged the project, and obtained in writing the opinions of learned men as to the best mode of executing it. He selected the plan of operations recommended by Mr. Hassler, the first Superintendent of the Coast Survey. This gentleman, a native of Switzerland, had been employed in the triangulation of the Canton of Berne, and had studied the science of geodesy under the most distinguished masters. It was exceedingly fortunate that his presence and advice here secured the early adoption of the only method of conducting a comprehensive trigonometrical survey that science approves, the only one of which the results have a certain and permanent value. It is only, however, since the year 1832 that the survey of the coast has been in steady and active operation.* * During this long interval of neglect on the part of the government, the coasting trade and foreign commerce of the country have been chiefly indebted to the indefatigable labors of those distinguished hydrographers, the Messrs. Blunt of New York, (both father and sons,) for the means of safe navigation. |