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Hilger & Watts Ltd., England



Serial Number



Telescope Length 146mm, Height 250mm


Hilger & Watts Micrometer Theodolite


This single-reading Optical Micrometer Theodolite is classified as a lower-order instrument and is generally used in detail surveys and setting-out work where high accuracy is not required. The telescope has a length of 146 mm, a clear objective aperture of 38 mm and a shortest allowable focusing distance of 1.6 m. The sensitivity of the altitude bubble, which is situated on top of the theodolite, and the plate bubble are 30" and 45" respectively. In this instrument the readings are taken only on one side of the horizontal circle (hence single-reading), however special precautions are taken in the design and manufacture of the instrument in order to keep the circle centering errors to a minimum. The graduation interval of the horizontal and vertical circles is 20 minutes and both these readings can be viewed through the same eyepiece.

The theodolite also incorporates a built-in optical plummet for centring over ground marks, and an optical micrometer. The micrometer permits direct reading of the circles to 20" and estimated to 5". The micrometer readings are read through an eyepiece which can be rotated to lie parallel to the vertical plane containing the axis of the telescope. This provides an advantage for the observer, since there is no need to move to the side of the instrument to take the reading. 

For overhead plumbing, a centring pin is fitted on the top of the telescope.


History & comments

There is no historical information available.


In a storage case




  • Telescope magnification is x 25
  • The instrument has a weight of 5.1 kg
  • The size of the rectangular storage case is 330 x 190 x 180 mm
  • Catalogued by T. Ko
  • Updated by F. Pall


Catalogued in 1997.

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