About the Archives Logo
The "theodolite", portrayed in the Archives logo, is a calibrated optical instrument used to determine  relative position in surveying, navigation, and meteorology. In essence, it is a telescope fitted with a spirit level mounted on a tripod with graduated scales that can measure the amount of rotation about it's vertical and horizonal axis. For example, timed measurements of the altitude and azimuth of a weather balloon are used to compute the estimated wind velocity of the atmosphere.
The evolution of theodolites began with the plane table alhidades, devices that allowed graphical mapping of terrain. These devices consisted of a plane table with a telescope mounted in a fork-like contraption or alhidade positioned along the horizontal plane. Using a piece of graph paper and a ruler horizontally aligned with the telescope, the position of the target could be plotted. The first description of a theodolite, or 'theodelitus', is found in the surveying textbook Pantometria by Leonard Diggs in 1571. The use of theodolites played a significant role in weather prediction during World War II.
Modern theodolites are equipped with an integrated electro-optical distance measuring device which allows for three dimensional free station position surveying. However, if you are so inclined, CSIRO Marine & Atmospheric Research provides an excellent instructional source for building your own theodolite.
The Archives logo was designed by Brannan McGill, Multimedia Services, UCAR. |
