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  Surveying Instrument Collection 


Wild, Heerbrugg, Switzerland


30° Prismatic Astrolabe Attachment for Theodolite (T2)

Serial Number



115 x 90 x 100 mm


Wild Astrolabe for T2


Astrolabe attachment for the telescope of Wild T2 theodolites.

It features a disk for the mercury horizon, a 60° equilateral prism for the deflection of the line of sight onto the mercury horizon and then upwards.

It carries a spot bubble and slow motion drive for the levelling of the device in trunnion axis direction.

The pool dish has a transport cover and a glass cover to protect the mercury pool during observations.

The case includes a glass bottle filled with mercury inside a protective wooden container, the top of which doubles as a funnel (when refilling the bottle ofter use). Also included are three 100 mm long glass rods of 3.5 mm diameter (to clean the mercury surface).

According to the manufacturer*, a series of eight star observations (two in each quadrant) deliver the latitude to 2-3" and the time to 0.2 s.

History & comments

ca 1963


in leather box 145 x 120 x 140 mm. Carrying strap brocken.


Minor paint damage. Mercury dish covered by a glued on metal plate. (The device is not funtional until this metal plate is removed.)


The box carries the label 'Wild G571 Astrolabe, 1 x Part No. 199898, 1 x Part No. 199899'

* see J. B. Mackie, The Elements of Astronomy for Surveyors, 9th ed, 1985, Charles Griffin & Co, High Wycombe, UK

The use of the device is discussed on pages 195-199 in R. Roelofs, Astronomy applied to Land Surveying, 1950, N.V. Wed. J. Ahrend & Zoon, Amsterdam


Catalogued in 2008 by JMR. Photo by JMR.

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