One Second Theodolite    
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  Surveying Instrument Collection 


Hilger & Watts Ltd, London, U.K.


No. 2 Microptic Theodolite (ST200-3)

Serial Number



160 mm diameter, 290 mm high


The instrument shown in the first b/w figure seems to be a later version of the theodolite in the collection. The second b/w figure shows the optical system of the horizontal circle reading The third b/w figure demonstrates the view in the micrometer eyepiece after adjusting the micrometer for the respective readings.

The black and white figures are from Clark, D. & Clendinning, J. 1954. Plane and Geodetic Surveying for Engineers. 4th ed. (1954 reprint), Constable & Company Ltd, London (pp.214-217, Figs. 91,92, 93)


Glass circle theodolite with optical micrometer (range 10'), with direct reading to 1". The instrument features diametrical circle reading and a coincidence reading altitude bubble. The reading telescope is on the outside of one of the standards. The micrometer has to be switched between horizontal and vertical circle readings and, thus, does not permit simultaneous readings of both circles.

The optical plummet is built into the alidade and, thus, rotates with the upper part of the theodolite. The vertical axis is made of hardened steel.

The instrument is wired internally for circle illumination. There are sockets (for the attachment of lights) near the mirrors for the horizontal and vertical circles and in the non-rotating base (for connection to a battery). The black-and-white figure above shows the attached lights for both circles rather than the mirrors.

Weight: 6.3 kg, with case 10.4 kg.

Telescope: Aperture 41 mm, magnification 28x.

Circle diameters: 98 mm (horizontal) and 76 mm (vertical).

Plate Bubble 20"/2 mm, altitude bubble 20"/2 mm

The instrument has a 5/8 inch Whitworth thread for centring in the base.

The transport container contains a broken eyepiece (for steep sights)

Technical data from "Hilger & Watts, Surveying Instrument Catalogue, 1960".

History & comments

Manufactured about 1950. More information on the instrument may be found in Clark, D. & Clendinning, J. 1954. Plane and Geodetic Surveying for Engineers. 4th ed. (1954 reprint), Constable & Company Ltd, London (pp.214-217), for example


in cylindrical metal case (diameter 260 mm, 362 mm high). The case is heavily rusted. The leather strap has been repaired.


Fully operational. Some paint damage.


The container has plaques for "Hilger & Watts Ltd, 98 St. Pancras Way, London, England" and for "E. Esdaile & Sons, Sydney".

The instrument was donated by Bill Rein, Balgowlah NSW, in April 2012


Catalogued on 25.3.2013 by JMR. Photo by JMR.

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