Webarchive template wayback links All articles with unsourced statements Articles with unsourced statements from December The first occurrence of the word “theodolite” is found in the surveying textbook A geometric practice named Pantometria by Leonard Diggeswhich was published posthumously by his son, Thomas Digges.
GUANGDONG KOLIDA INSTRUMENT CO .LTD
A transition was brought about by Breithaupt and the symbiosis of Utzschneider, Reichenbach and Fraunhofer. In other projects Wikimedia Commons. Modern theodolites are usually of the transit-theodolite design, but engraved plates have been replaced with glass plates designed to be read with donload diodes and computer circuitry, greatly improving accuracy.
He also described an instrument that measured both altitude and azimuth, which he called a topographicall instrument [ uee ]. Wikimedia Commons has media related to Theodolites.
This was the transit theodolite. It uses a spirit level to set a telescope level to define a line of sight along a horizontal plane. Later instruments had a single alidade on the vertical semicircle and the entire semicircle was mounted so as to be used to indicate horizontal angles directly.
Theodolite – Wikipedia
The gyrotheodolite comprises a normal theodolite with an attachment that contains a gyroscope mounted so as to sense rotation of the Earth and from that the alignment of the meridian.
Before use, a theodolite must be precisely placed vertically above the point to be measured using a plumb boboptical plummet or laser plummet. When the telescope is pointed at a target object, the angle of each of these axes can be measured with great precision, typically to milliradian or seconds of arc. There is some confusion about the instrument to which the name was originally applied.
Where this extra precision is not required, the gyrotheodolite is able to produce a result quickly without the need for night observations. The intersection of the meridian plane with the horizontal contains the true north-south geographic reference bearing required.
A gyrotheodolite can be operated at the surface and then again at the foot of the shafts to identify the directions needed to tunnel between the base of the two shafts. From Wikipedia, the free encyclopedia. Some identify the early theodolite as an azimuth instrument only, while others specify it as an altazimuth instrument. Measuring and alignment tools. The balloons are carefully constructed and filled, so their rate of ascent can be known fairly accurately in advance.
It must be restarted again at each site. An alidade on the base was used to sight an object for horizontal angle measurement, and a second alidade was mounted on the vertical semicircle. In a transit theodolite, the telescope can be inverted in the vertical plane, whereas the rotation in the same plane is restricted to a semi-circle in a non-transit theodolite. This technique is called a resection solution or free station position surveying and is widely used in mapping surveying.
There is a long history of theodolite use in measuring winds aloft, by using specially-manufactured theodolites to track the horizontal and vertical angles of special weather balloons called ceiling balloonsor pilot balloons or pibal.
When available, astronomical star sights are able to give the meridian bearing to better than one hundred times the accuracy of the gyrotheodolite. The instrument is then set level using pddf footscrews and circular and more precise tubular spirit bubbles. The theodolite became a modern, accurate instrument inwith the introduction of Jesse Ramsden ‘s famous great theoodolitewhich he created using a very accurate dividing engine of his own design.
Denham discover this technology in In the early part of the 20th century, Heinrich Wild produced theodolites that became popular with surveyors. Typically, ruggedized laptopsPDAs or programmable calculators  are used as data collectors for this purpose.
This can be tested by aligning the tubular spirit bubble parallel to a line between two footscrews and setting the bubble central. The Ramsden theodolite was used over the next few years to map the whole of southern Britain by triangulation. Both axes of a theodolite are equipped with graduated circles that can be read through magnifying lenses.
Modern triangulation as, e. Theodolites were later adapted to a wider variety of mountings and uses. If not, then a “collimation error” exists.
In today’s theodolites, the reading out of the horizontal and vertical circles is usually done electronically with a rotary encoder. The meridian is the plane that contains both the axis of the Earth’s rotation and the observer. With continuing refinements instruments steadily evolved into the modern theodolite used by surveyors today.
Levels / Theodolites | Products | Positioning | TOPCON
A theodolite may be either transit or non-transit. Nowadays GPS antennas used for geodetic positioning use a similar mounting system. Navy to take the first precision surveys of American harbors on the Atlantic and Gulf coasts. Half of the difference between the two positions is called the “index error”.
The meridian is undefined at the geographic poles. A theodolite measures vertical angles as angles between the zenith, forwards or plunged—typically approximately 90 and degrees.
Some types of transit theodolites do not allow the measurement of vertical angles. Erasmus Habermehl in Germany incomplete with compass and tripod. Unlike an artificial horizon or inertial navigation system, a gyrotheodolite cannot be relocated while it is operating.
A gyrotheodolite will function at the equator and in both the northern and southern hemispheres. Retrieved from ” https: Their existence is taken into account in the choice of measurement procedure in order to eliminate their effect on the measurement results of the theodolite.
The height of the reference point of the theodolite—or the target—above the ground benchmark must be measured precisely.