The vertical circle is a sturdy instrument designed for precise measurement of the altitude of a celestial body. The first important example was the very large vertical circle that was made by Jesse Ramsden in London, and installed in the astronomical observatory in Palermo in 1789. Another famous example was built by Ertel in Munich, and installed in the Pulkowa Observatory, near St. Petersburg, Russia, in 1839. Smaller and more portable vertical circles designed for geodetic work were use by the 1840s.
Ref: William Chauvenet, A Manual of Spherical and Practical Astronomy (Philadelphia, 1863), vol. 2, pp. 315-319, and plate XI.
