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  Surveying Instrument Collection 


Wild, Heerbrugg (Switzerland)



Serial Number



Height 340mm


 Wild RDH Horizontal Staff Tacheometer


This is a direct scale-reading tacheometer which is particularly useful for precise traversing and cadastral work in high-priced terrain. A special horizontal staff is used with the instrument which allows the reading of not only the horizontal distance, but also the difference in elevation between the instrument and the staff. A simple reversing knob serves for changing over from the horizontal distance to the difference in elevation, or vice versa. The distance and height accuracies per 100 metres is considered to be about 1-2 cm and 3-5 cm respectively, which is adequate for nearly all applications.

The instrument features a bright image telescope with 25x magnification, and is reversible on the objective side. The clear objective diameter of the telescope is 45 mm, and the eyepiece can be turned to change the telescope over from single image operation for angle measurements to double image operation for staff reading. The maximum range between the staff and the telescope is about 150 metres, however using special staves, this can be increased up to 200 metres. The shortest target distance is about 5 metres.  

A scale microscope is situated beside the telescope eyepiece which enables the horizontal and vertical scales to be directly read to 1 minute and estimated to 6 seconds. The sensitivity of the plate level and collimation level is 30" per 2 mm. The numerals on all scales to be read on the instrument and staff increase from left to right, thus helping to prevent gross errors in reading.

History & comments

This horizontal staff tacheometer is based on a design patented by Bosshardt in 1923.


In a rectangular metal case




  • This instrument is one of the two kinds of direct-reading tacheometers included in the collection. The other tacheometer is a Vertical Staff Tacheometer, the Wild RDS
  • Catalogued by T. Ko
  • Updated by F. Pall


Manufactured in 1955 (approx). Catalogued in 1997

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