- Domeniu: Earth science
- Number of terms: 93452
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- 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, ...
The iron bar of one metre length brought to America in 1805 by Ferdinand R. Hassler, the first superintendent of the U. S. Coast Survey, for use by that survey as a standard of length. The Committee Metre was one of sixteen such bars calibrated by the Committee on Weights and Measures in Paris in 1799 against the Prototype Metre. It served as the standard of length for geodetic surveys in the United States of America until 1889 or 1890, when it was replaced by the National Prototype Meter. The Committee Metre was presented by Hassler to the American Philosophical Society in Philadelphia.
Industry:Earth science
A copy made by placing the original, in black lines on a transparent material, in contact with a paper sensitized with ferrocyanic salts and illuminating the original. The exposed paper is developed in a bath of water and shows the original pattern in white lines on a blue background.
Industry:Earth science
A profile plotted from data obtained by surveying, and used to check a profile plotted from measurements on a topographic map.
Industry:Earth science
A surveyor's compass which has attached to it a radial arm with a vertical, slotted strip at each end. The surveyor sights through the two slots at an object and then, by raising his eye slightly, sees and reads off the direction shown on the compass.
Industry:Earth science
(1) A camera used for photographing rockets or missiles, and producing photographs with sufficient metric fidelity that the object's trajectory can be determined photogrammetrically. Erroneously called a tracking camera. A ballistic camera may be of the fixed or the tracking type. A fixed ballistic camera keeps its optical axis pointed in the same direction while taking many pictures, and a photograph made by the camera shows the missile as a thin streak interrupted by spacings made by opening and closing the camera's shutter. A tracking ballistic camera keeps its optical axis pointed in the general direction of the object being photographed, and a photograph made by such a camera shows the object as a dot; the mounting often carries one or two graduated circles to show the direction in which the camera is pointed (this may be photographed or transmitted by selsyn motors to a recorder). (2) Any camera used in ballistics.
Industry:Earth science
(1) The second order differential equation ρ((d ²f/dR ²) (6f/R ²)) + (6ñ/R)((df/dR) + (f/R)) = 0 relating the flattening f of a rotational ellipsoidal solid composed of homogeneous, ellipsoidal shells and of average radius R and density ρ(R). Sometimes referred to as Clairaut's equation. It has been generalized (e.g. by Jeffreys) by replacing f by fn, where fn is the n-th coefficient in an expansion of r/R in zonal harmonics. The factor 6 in the equation is then replaced by n(n+1). (2) The first order differential equation y = x(dy/dx) + f(dy/dx). Its solution is.
Industry:Earth science
The detection of a change in object space by looking for changes in the images made of that object-space.
Industry:Earth science
A tower used in triangulation and consisting of two braced tripods, one within the other, constructed, according to the design of J. S. Bilby, so that an observer on a platform at the top of the outer tripod can move about without disturbing an instrument mounted on the top of the inner tripod. The Bilby tower was put into use in 1927 and is standard equipment in triangulation done by the U. S. National Geodetic Survey. The tower can easily be put up, taken down, and moved to a new location. It is also durable. Because the original Bilby tower and most subsequent ones of that design have been built of steel, the tower is often referred to as the Bilby steel tower.
Industry:Earth science
Assembling a strip mosaic from aerial photographs with more than 50% overlap by matching a point near the center of one photograph with corresponding points in the overlap of adjacent photographs.
Industry:Earth science
