Special Publications, Edição 145U.S. Government Printing Office, 1935 |
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Palavras e frases frequentes
accuracy adjustment alidade azimuth base measurement best chains bubble catenary central-point figure chief of party clamp có có có Coast and Geodetic computation concrete determined difference of elevation direction theodolite discrepancy eccentric eleva elevation Correc errors due exceed eyepiece field first-order formula forward stake GEODETIC SURVEY Form geographic positions grade corrections graduated circle inches instrument intersection stations invar tape kilograms Latitude line of sight located logarithms main scheme mean measured length method micrometer miles necessary nomogram object observations obtained Polaris pole probable error quadrilateral reading rear contact reconnaissance record reduced reference marks refraction repeating theodolite second-order traverse second-order triangulation set-up shown in Figure side sighting devices signal Special Publication spherical excess station mark stretcher surface tape length telescope temperature tension terminal stations third-order traverse line triangulation and traverse triangulation station tribrach tripod usually vernier vertical circle zenith distance
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Página 9 - To compare two alternative figures, either quadrilaterals or central point figures, for example, with each other in so far as the strength with which the length is carried is concerned, proceed as follows: (a) For each figure take out the distance angles, to the nearest degree if possible, for the best and second best chains of triangles through the figure. These chains are to be selected at first by estimation, and the estimate is to be checked later by the results of comparison. (Z>) For each triangle...
Página 107 - Reference marks Note 11. — A standard disk reference mark with the arrow pointing toward the station set at the center of the top of (a) a square block or post of concrete, (6) a concrete cylinder, (c) an irregular mass of concrete.
Página 107 - Note 13. — A standard disk reference mark with the arrow pointing toward the station set in concrete at the center of the top of a tile, (a) which is embedded in the ground, (b) which is surrounded by a mass of concrete, (c) which is fastened by means of concrete to the upper end of a long wooden pile driven into the marsh, (d) which is set in a block of concrete and projects from 12 to 20 inches above the block. Witness marks.
Página 107 - ... station mark, (6) a copper bolt projecting slightly above the concrete, (c) an iron nail with the point projecting above the concrete, (d) a glass bottle with the neck projecting a little above the concrete, (e) an earthenware jug with the mouth projecting a little above the concrete. Note 8. — In bedrock (a) a standard disk...
Página 35 - It should be 16 inches in diameter for the top 2% feet and 10 inches in diameter at the lower end. Concrete made of good cement, sand, and gravel or broken rock is placed in the lower part of the hole to a depth of 6 inches. A standard tablet station mark (fig.
Página 104 - Of equal importance to the future recovery of the station is the description of the station, which should be clear, concise, and complete. The first part of the description should enable one to go with certainty to the immediate vicinity of the station, while the latter part, the detailed description, by its measured distances to reference marks and its description of the station marks must inform the searcher of the exact location of the station and make its identification certain. The...
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Página 8 - B y ) depend entirely on the figure chosen and are independent of the accuracy with which the angles are measured. The product of these two terms is, therefore, a measure of the strength of the figure with respect to length, in so far as the strength depends on the selection of stations and of lines over which observations are made. Hence, the strength of...