86. Repeating theodolite by Ertel & Sohn
Munich, c. 1840
Traugott Lebrecht Ertel (Freiburg 1778-Munich 1858)
Georg Ertel (Munich 1813-1863)

diameter divided circle 35 cm
diameter vertical circle 15 cm
length of telescope 42 cm
[Inv. MdS-80]

The repeating theodolite is an instrument used basically for geodetic measuring. Though different in design to the repeating circle the two are nonetheless conceptually similar, both using the method of repetition (or multiplication) of angles.
This is a single telescope model. On top of the telescope is the level [Inv. MdS-88], used for checking the horizontality of the instrument. The telescope still has its optical parts and cover. The inner circle carries the vernier for measuring, done by means of two microscopes supported on a rotating arm, while the outer circle has a graduated limb in silver; the inscription Ertel & Sohn in München can be read. For details on Traugott and George Ertel see file 22 on the Meridian Circle and, for further information, the books by Repsold and Bennett (op. cit.).

J.A. Bennett (1987), pp. 155, 160.
E. Miotto, G. Tagliaferri, P. Tucci, pp. 55, 111.
J.A. Repsold (1908, 1914).