During the first half of the nineteenth century, the term “transit” was popularized in America. The transit was fundamentally a theodolite in which its telescope could be completely rotated 360 degrees in a vertical plane around the horizontal axis. This enabled back-sighting and fore-sighting on opposite sides of the vertical circle and doubling of angles resulting in more accurate line production and measurement of angles.
In this section instruments that are included, are named transits by their manufacturer, which most often are North America and some non-european countries. As well theodolites manufactored in Europe were often called transit theodolites meaning they were a theodolite that could be transited (rotated 360 degrees in a vertical plane around the horizontal axis).
In researching transits and/or theodolites it is adviseable to review these instruments under both headings in the collection.
The following “transits” are part of the Society’s collection.
Transit, Path Instruments
Transit, Astra
Transit, Keuffel & Esser
Transit, Topley
Transit, Westec
Transit, Dietzgen
Transit/Level, Adie
Photo Theodolite, Galileo
