- Industry: 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 compass having the line of sight deliberately placed tangent to the rim of the compass.
Industry:Earth science
(1) A telescope having motion only about a horizontal axis. e.g., a meridian circle is a telescope having movement only in the plane of the meridian. (2) A circular disk or ring whose perimeter is graduated in angular units. A circle in a surveying instrument is perpendicular to an axis of rotation and has its center on that axis. It is called a horizontal circle if it is intended for measuring horizontal angles and is called a vertical circle if it is intended for measuring vertical angles. Many instruments do not require a circle's full 360<sup>o</sup> and use only a sector of a circle. These sectors and often the instruments containing them, are then called quadrants, sextants, or octants according as they comprise 1/4-th, 1/6-th or 1/8-th of a circle.
Industry:Earth science
That vector which, at a point on a curve, forms a right handed set with the positive tangent and the positive normal, in that order.
Industry:Earth science
A hand-held compass containing a liquid that damps the motion of the needle.
Industry:Earth science
A terrestrial camera used to photograph lighted objects or lights at considerable distances above the ground and against a background of stars. The object may be the Moon, a flare, a light carried on an artificial satellite, etc. Glass plates are usually used instead of film.
Industry:Earth science
A card having a list of calibration corrections or calibrated values.
Industry:Earth science
The ideal position of the line of sight of a telescope - that is, the optical axis. This definition may be self contradictory.
Industry:Earth science
The line, along a street, midway between the sides of the street. The term usually applies to the center line of the original street, before its widening or closing. To avoid ambiguity, if the street has been narrowed or widened on one side or unequally, the center line would be defined as the center line as existing on (a specified date). closing; i.e., the center line of the original street midway between the sides.
Industry:Earth science
The time of an event, designated by giving the Besselian year in which the event occurred and the fraction of the Besselian year that had passed since the beginning of that year. Because the Besselian and tropical years are of nearly the same length, it is customary to give the fraction of a tropical year rather than the fraction of a Besselian year.
Industry:Earth science
The intersection of a tidal datum with the land. This definition permits many intersections to be included which are not boundaries. The intersection should be specified, otherwise, as one which is also legally a boundary.
Industry:Earth science
