2-inch altitude-azimuth universal telescope


2-inch altitude-azimuth universal telescope


Measuring instrument
Optical instrument


Wood, metal, glass

Stored in 2 large wooden boxes (22 ¼ x 12 ½ x 14 ¼ and 22 x 22 ½ x 17 inches). Transit consists of base with three leveling screws, telescope, striding level, 3 eyepieces, several lens caps for the eye pieces and an objective light shield. Silver vernier scales are tarnished, brass reading microscopes and micrometers are pitted in places, black paint on telescope tube also pitted. Three spirit levels on base (two perpendicular to telescope one parallel) all functional. Inscribed “Troughton and Simms London” on the support for the horizontal tangent screw and “obs 62” on base by the reading microscope A.

Myers’ description of the instrument: "This instrument was made by Troughton and Simms, has an aperture of 2-inches and a focal length of 20-inches. Its horizontal and vertical circles are each 12-inches in diameter, graduated on silver to 5 minutes and read by two reading microscopes to single seconds. Tenths of seconds are readily estimated. It is provided with both fine and coarse levels for adjustment to place, an accurate striding level, and a very complete set of eyepieces. The reticle consists of nine vertical and three horizontal cross hairs, illuminated by a lamp at the end of the axis. Both vertical and horizontal circles shift for position, this instrument being the first to have a shifting vertical and among the first to have a shifting horizontal circle."

Article describing the theodolite from 1882: “A theodolite, constructed by Troughton & Simms, of London, at a cost of about $700, has been added to the equipment of the Civil Engineering Department. It is an ‘Altitude and Azimuth’ or ‘Universal’ instrument; that is, both vertical and horizontal angles can be read with it. It is the finest and best form of the most accurate engineering instrument that has, as yet been made, having all the most modern improvements. The two circles - the most important part of the instrument - are twelve-inches in diameter and graduated to five-minute divisions. Upon each, the further reading is effected by the help of two micrometers and verniers, directly to seconds; each circle may be shifted between sets of observations, and by thus reading the angle on different parts of it, any error in the graduation is thus eliminated. The telescope is superior to either of the two now in the Observatory. It was intended to mount the theodolite permanently in the Observatory with the other instruments, but the manufacturers have send a tripod, and now the instrument may be used at any point desired.

“The money, with which to buy this instrument, was appropriated in 1871, but when taxes were abated in Chicago, after the fire, the appropriation for the new building was cut off, and this money was used in its place. In 1873, another appropriation was made, but for some reason the matter was dropped until last May, when a third appropriation was made. In July an order for the instrument was send to London, and it was completed and shipped about January 1, of this year. The theodolite is to be used in the classes in Geodesy and Practical Astronomy."

This instrument was used to observe the December 6, 1882 transit of Venus across the Sun.

A 1954 survey of the instruments by J.W. Fecker Inc. noted “This instrument is in poor condition as a result of extreme neglect and many small parts appear to be missing. The considerable expense involved in reconditioning this unit might be inadvisable unless an immediate need existed for the instrument. We suggest that no reconditioning be undertaken in the absence of such need. We do recommend that the instrument be carefully reconditioned as to finish only by interested and capable students and then used temporarily as an exhibit item in the observatory entrance foyer.”


Troughton & Simms, London


Myers, G.W. (1898) The Astronomical Observatory. Technograph. 11: 105-111.

The New Theodolite. April 1, 1882, The Illini, p. 10.

Transit of Venus. December 9, 1882. The Illini, p. 8.


Astronomy Department, University of Illinois, Urbana, Illinois




Michael Svec


Copyright Michael Svec






physical object


University of Illinois Observatory Collection A113
University ID 016648, obs 62


University of Illinois Observatory, Urbana, Illinois


Troughton & Simms universal transit telescope



Troughton & Simms, London , “2-inch altitude-azimuth universal telescope,” University of Illinois Observatory Collection, accessed August 16, 2017, http://uiobservatory.omeka.net/items/show/7.