1999 Wild NA2-GPM3 combination.

The Wild Heerbrugg NA2/GPM3 combination.
Figure 1: The Wild Heerbrugg NA2/GPM3 combination.
This was a superb donation to my collection in 2009. Being a left-over in an inventory, the previous owner had little use for it and decided it would fit better in my collection than on the market. Made by Wild Heerbrugg the instrument is of Swiss origin and signed both 'Leica' on one side and 'Wild NA2' on the other. The instrument is the direct successor of the Wild N2 in my collection.

The NA2 was originally developed by Wild in 1960 and modernised in 1981. After Wild Heerbrugg merged with the Cambridge Instrument Company plc to form the new Leica Holding B.V. group on April 2nd, 1990,1 Leica continued the production of the Wild instruments and this is why both company names are shown on the instrument (see figure 3 and figure 4).

This particular NA2 was sold to the Netherlands in January 1999, while the GPM3 parallel plate micrometer on top of it dates from 1982.2

The Wild NA2/GPM3 combination from the other side.
Figure 2: The Wild NA2/GPM3 combination from the other side.
Accuracy
With only the Wild N3 being more accurate the NA2/GPM3 combination is a much more sophisticated instrument than the NK10 in my collection. Similar to the 1960s Zeiss Opton Ni 2 it is a combination of a compensated level and a separate parallel plate micrometer that allows readings down to 0.1 millimetres, while estimating another decimal is possible. The settling accuracy of the compensator is about 0.3" (0.04mm at 25 metres). The original 1960 model allowed to level a 1km double run - using the parallel plate micrometer - with an accuracy of 0.4mm (1σ, 68%), while this modernised version was further improved to 0.3mm (1σ, 68%).

Unlike the NK01 and NK10 this NA2 has no horizontal circle in its base. The 'K' in the type number of the first two indicates whether or not a level has a horizontal circle ('Kreis' in German). Equipped with a horizontal circle this instrument would then have been a NAK2.

Notes

[1]: http://www.wild-heerbrugg.com/History.htm
[2]: Many thanks to Jürg Dedual from the Swiss Wild Heerbrugg virtual archives for checking the selling date and manufacturing year for me.

If you have any questions and/or remarks please let me know.

The Wild NA2 without the GPM3 plan parallel plate micrometer.
Figure 3: The Wild NA2 without the GPM3 plan parallel plate micrometer.
 
The Wild NA2 without the GPM3 plan parallel plate micrometer from the other side.
Figure 4: The Wild NA2 without the GPM3 plan parallel plate micrometer from the other side.

The Wild NA2 and GPM3 separated.
Figure 5: The Wild NA2 and GPM3 separated.
 
The serial number of the Wild GPM3 parallel plate micrometer.
Figure 6: The serial number of the Wild GPM3 parallel plate micrometer.

A close-up of the Wild GPM3 plan plate.
Figure 7: A close-up of the Wild GPM3 plan plate.
 
The Wild NA2/GPM3 combination with is case in which it fits without dismantling.
Figure 8: The Wild NA2/GPM3 combination with is case in which it fits without dismantling.

Two distant relatives; the Wild NA2 and Wild NKII.
Figure 9: Two distant relatives; the Wild NA2 and Wild NKII.
 
The Wild NA2/GPM3 compared to the Zeiss Opton Ni 2.
Figure 10: The Wild NA2/GPM3 compared to the Zeiss Opton Ni 2.

The Rijkswaterstaat sticker showing their former Kanaalweg address.
Figure 11: The Rijkswaterstaat sticker showing their former Kanaalweg address.
 
The Rijkswaterstaat inventory number on the GPM3 and Leica logo on the NA2.
Figure 12: The Rijkswaterstaat inventory number on the GPM3 and Leica logo on the NA2.

The Wild NA2 Rijkswaterstaat inventory number and Wild logo.
Figure 13: The Wild NA2 Rijkswaterstaat inventory number and Wild logo.
 
The circular vial of the Wild NA2.
Figure 14: The circular vial of the Wild NA2.

The circular vial of the Wild NA2 can be observed through a prism above it.
Figure 15: The circular vial of the Wild NA2 can be observed through a prism above it.
 
The erect view through the telescope revealing the typical Dutch cross-hairs.
Figure 16: The erect view through the telescope revealing the typical Dutch cross-hairs.

The erect view through the telescope with the cross-hairs correctly set by the plan parallel plate.
Figure 17: The erect view through the telescope with the cross-hairs correctly set by the plan parallel plate.
 
The corresponding reading of the GPM3.
Figure 18: The corresponding reading of the GPM3.

Surveyor's crosses Geodetic Sextants Theodolites Total Stations Levels Standards Tools Firms
20th c. hydrostatic level 19th c. water bottle level 19th c. Secrétan Egault 19th c. Tibaut Lenoir 1928 Carl Zeiss Nivellier I 1926 Wild NKII 1924 Carl Zeiss Nivellier II 1948 Wild N1 1932 Carl Zeiss Nivellier III 1951 Wild N2 1965 Wild NK01 1965 Wild NK10 1961 Wild N3 1970 Wild NK2 1977 Wild N3 1999 Wild NA2-GPM3 20th c. Cowley 1960s Jenoptik Koni 007 1960s Zeiss Opton Ni 2