civil engineering portal

A surveyor instrument having a short telescope fixed rigidtly to a horizontal rotating table.

A theodolite   is a precision instrument for measuring angles   in the horizontal and vertical planes. Theodolites are mainly used for  surveying  applications, and have been adapted for specialized purposes in fields like metrology . A modern theodolite consists of a movable telescope mounted within two perpendicular axes — the horizontal  or trunnion  axis , and the vertical axis. When the telescope is pointed at a target object, the angle of each of these axes can be measured with great precision, typically to seconds of arc.

work of  a surveyor consists of following three sections........ 1.field work. 2.office-work. 3.care and adjustment of instruments. 1.field-work:- this includes taking measurements for details, recording field-notes and setting of work. 2.office work:-it consists of preparing maps,plans and sections from the  data collected  in the field and also calculating areas and volumes and designing various structures. 3.care and adjustment of instrument:- a surveyor must be thoroughly  familiar with the instrument.He must knows the appropriate method of using instrument because even a minor injury to instrument is liable to make them out of order.

Surveying techniques have existed throughout much of recorded history. Under the Romans, land surveyors were established as a profession, and they established the basic measurements under which the Roman Empire was divided,  such as a tax register of conquered lands (300 AD). In the 18th century in Europe triangulation was used to build a hierarchy of networks to allow point positioning within a country. Highest in the hierarchy were triangulation networks. These were densified into networks of traverses  (polygons), into which local mapping surveying measurements, usually with measuring tape, corner prism and the familiar red and white poles, are tied.

The  following two basic principles should be considered while determining relative position of points on the surface of earth:- 1. determining suitable method for locating a point:- it is  always practicable to select two points in the field to measure the distance between them. These can be represented on paper by two points placed in a convenient positions. 2.working from whole to the part:- in surveying an area, it is essential to establish first of all a system of control points with great precision. Minor control points can then be established by less precise method and the details can be located  afterwards by method of triangulation or traversing between control points.  Know the basic and you will never need to know again and again.

测量 是 确定 物体 的相对位置 earth.Surveying 或 土地测量 表面 上 的 艺术 ，是 技术， 专业和 科学 准确地确定 点 和 them.Surveying 之间 的距离和 角度 的 地面 或 三维位置 一直 以来 有记载的历史 （ 5000年前 ） 开始 在 人类生存环境的 的 发展 的 基本要素 。 这是 需要 在规划 和 执行 几乎所有的 建筑形式 的 ..

IT  is a branch of survey which helps in determination of elevation of a given point or object with espect to some specified point or object. . Common levelling instruments include the spirit level , the dumpy level , the digital level, and the laser level. The dumpy level is an older style of optical instrument. It is commonly believed that dumpy levelling is less accurate than other types of levelling, but such is not the case. Dumpy levelling requires shorter and therefore more numerous sights,   but this fault is compensated by the practice of making foresights and backsights equal.

there are two main types of survey. 1.plane survey. 2.Geodetic survey. Plane survey:-I n plane survey the surface of earth assume as plane or straight its uses as limited distance. Geodetic survey:- in geodetic survey surface of earth assume as curve its use in long distance.

surveying  is the art of determining the relative positions of objects on the surface of earth. Surveying  or land surveying is the technique, profession and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them. Surveying has been an essential element in the development of the human environment since the beginning of recorded history (about 5,000 years ago). It is required in the planning and execution of nearly every form of construction..