History of a theodolite
Geographical maps of XVII century were the present true works of art and quite often used as an ornament for an interior.
Let's look at the Map of Russian Empire made in 1726. Shooting then was much less exact, and scientific methods of displaying are not developed yet. Therefore outlines of coastal lines, channels of the rivers and other details of a relief on it appear differently, than on modern maps.
Some point from Theodolite’ predecessor history. Exact tool shooting of district in Russia have started to carry out in the first quarter of XVIII century. Approximately during same time the special geodetic tool - keepregel - has been invented. Its telescope is rigidly fastened to a ruler intended for construction in field conditions of lines on the plan, spread out on a special little table. For example there is - keepregel released of 1898. Its sector scale is intended for measurement of corners of an inclination of a line of vising to within 5 angular minutes.
Theodolite is shooting on district. In a telescope with greater increase - the theodolite - is taken with readout on with divisions which serially put in points of measurements. So receive excess - differences of heights between points of district.
The modern electronic theodolite measures corners to within 1,5 angular seconds. It is supplied with special processor, recording data in a digital kind. The written down information is processed by a stationary computer and removed on plotter which builds the plan of district to within 0,01 millimeters.
The laser level with a rotating prism can move a beam both in horizontal and in a vertical plane, allowing quickly mounting ideally equal walls and blockings.
The laser level with the electronic device on measures height concerning "zero" to within 0,8 millimeters on distance up to 150 meters.
Satellite geodetic system, GPS Total Station is the most perfect on today that enables to accept signals simultaneously from several satellites on the aerial with a flat reflector. The equipment measures distances and heights with an error of 5 and 10 millimeters accordingly plus of one millimeter on each kilometer.
Global satellite systems GLONASS (Russia) and GPS (USA) allow to find practically instantly coordinates of any points on a surface of the Earth and distances between them with high accuracy. Systems work in modes of code and phase measurements.
A. In the first case one complete set of the ground equipment GPS Total Station accepts the coded signals simultaneously from four satellites, position in which orbit very well-known. On a difference of time of arrival of signals position of a point in space pays off.
B. In the second case two complete sets of the GPS Total Station equipment work. They accept signals from satellites all over again during one moment of time (continuous lines), and then - in another (dashed lines). Signals come with different phases; on their difference also find distance between points of measurements.
The portable surveying instrument that we call a theodolite was invented in the middle of the sixteenth century by Leonard Digges of Kent, who gave it a name that was expressed in the common Latinate form of the time: theodelitus.
(The name changed to an Anglicised form later, and at that time the e in the middle shifted to o for no very good reason anybody can discover.) His theodolite, by the way, was not quite the same as the modern device, since it consisted of a circle for measuring horizontal angles only.
It was described in a book that was published posthumously by his son Thomas in 1571: A Geometricall Practise, named Pantometria, divided into Three Bookes, Longimetria, Planimetria, and Stereometria, containing Rules manifolde for Mensuration of all Lines, Superficies, and Solides (but then you knew that).
The evolution of the theodolite began with the description of the instrument included within the book Pantometria, by Leonard Diggs in 1571.
The Ramsden theodolite is a large theodolite (American English: transit) which was specially constructed for use in the first Ordnance Survey of Southern Britain.
The theodolite was commissioned from Jesse Ramsden, a leading Yorkshire instrument maker, who had developed the technique of dividing angular scales accurately to within a second of arc.
The Ramsden theodolite was used over the next few years to map the whole of southern Britain by triangulation.
Jesse Ramsden was appointed to build a theodolite that was capable of the accuracy required for such surveys.
The Great Theodolite continued being used for important surveys and is now housed in the Greenwich Museum in England.
Buff and Buff Theodolite In the 1920's this was the mainstay of U.S. Meteorological Observations until the adoption of the David White Series exemplified by he 6061 below.
The theodolite illustrated here is a vernier type and is seen in publications from the 1920's military and civilian.
This theodolite acquired from R and A Rost of Vienna Austria is more recent variant of the Kölzer-Sprenger Berlin theodolite.