Wild Heerbrugg MS1 Polaris attachment
Wild Heerbrugg MS1 Polaris attachment
Obtained from the Netherlands
This is a very rare attachment to the Wild Heerbrugg theodolite. It comes from the collection of John Vossepoel and I was happy to add it to my collection. I had to do some research (and buy the manual) to figure out how to operate it. The attachment has two prisms and a rotary scale. After reading the manual (still need to try it at night) it should work as follows (but only in the Northern hemisphere).
The instrument is pointed at Polaris (alfa ursa minoris) after which the attachment is placed (and a small correction made to keep it into view). Now beta ursa minoris is brought into the middle of Polaris by rotating the attachment. The measurement is repeated with the other face of the telescope. The horizontal circle now indicates true north (astronomic north). The vertical circle is nearly the latitude whereas the scale on the prism can be used to determine stellar time with the tables in the manual.
As the stars move relative to the earth axis (or rather vice versa) each attachment is set up for a specific year (on this 1960) and corrections need to be applied for any year after the year for which it is set.
MS1
Data sheet
- Year
- c1960
- Serialnumber
- 1790
- Type of use
- Survey
- graduation
- hours
- measuring range
- 24
- diameter scale in mm
- 50
- accuracy
- 1
- fine reading
- direct (analog)
- weight instrument in kg
- 0.33 + 0.42
- Size case (l x w x h) in m
- 0.07 x 0.05 x 0.07
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Wild Heerbrugg MS1 Polaris attachment
Obtained from the Netherlands