- Branche: Earth science
- Number of terms: 93452
- Number of blossaries: 0
- Company Profile:
Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
A punched card having eighty vertical columns each containing the numbers from 1 to 12, the instruction or data being determined by which numbers are punched out.
Industry:Earth science
A stake driven into the ground near a marker (hub), usually sloped so that the top of the stake is over the marker. The guard stake protects, and its marking identify, the marker.
Industry:Earth science
A transparent, plastic sheet for laying over a map, having a family of concentric circles and a family of corresponding radii drawn on it according to a scheme devised by S. Hammer, so that the angles between radii and the spacings between circles simplify the calculation of topographic gravity-corrections for geophysical exploration. The template and its accompanying tables were improved by J. Bible (1962) and by V. Douglas and S. Drahl in 1972, to allow calculation to 0.1 mgal. The tables have been further simplified by presentation in the same form as the luni-solar gravity correction.
Industry:Earth science
The process of determining theoretical values of gravity at a number of points on the Earth's surface from measurements made at those points. Gravity adjustment is usually done so that the resulting theoretical values are the best approximation, in a statistical sense, to the measured values.
Industry:Earth science
(1) The receiver for the echoes produced in echo sounding. (2) A device for listening to or detecting sound in water.
Industry:Earth science
(1) A quantity added to a theoretical value of gravity or subtracted from a measured value to account for the gravitational attraction of the Sun and Moon on the gravimeter or other instrument. (2) A correction applied to measurements of gravity to remove the effect of earth tides on the measured values. It is commonly included in the drift correction and may be determined by a series of observations at a fixed base station. (3) A correction applied to the measured period of a pendulum to take into account the effect of earth tides. If the Earth were rigid, the Moon and Sun at the zenith would decrease the magnitude of gravity acceleration by about 0.16 and 0.08 mgal respectively, relative to the values when the Moon and Sun are on the horizon. Because of the yielding of the crust and sea, the effect is a little greater than it would otherwise be. The amount is not entirely predictable and is usually ignored.
Industry:Earth science
The hour angle between the meridian of the Mean Observatory and the true vernal equinox of date.
Industry:Earth science
A map printed in a subdued monochromatic hue such as gray blue and used as a base for overprints.
Industry:Earth science
A line projected northward along an astronomical meridian, from a point established on the base line or on a standard parallel, and on which township, section, and quarter-section corners are established. Guide meridians are usually spaced at intervals of 24 miles east or west of the principal meridian.
Industry:Earth science
