1977 Wild Heerbrugg N3 new style

The 1977 new style Wild Heerbrugg N3.
Figure 1: The 1977 new style Wild Heerbrugg N3.
A few weeks after I bought two 1960s Wild N3's for a product development within my company, a client who heard about it decided to donate this instrument to my collection. Judging from the impeccable state it is in, the instrument has spent little time in the field. The instrument was the latest version of the Wild N3 and design-wise it is very similar to the Wild TC1 in my collection which also dates from the same period.

The instrument is of Swiss origin, from the same manufacturer as the NKII, NK01, NK10, N2 and NA2 in the collection. The N3 was the top model of Wild Heerbrugg and - compared to other uncompensated levels - still is unsurpassed in accuracy.

Provenance
The instrument once belonged to the Survey Department (Meetkundige Dienst) of the Dutch government. Not only can this be seen by the inventory number, but also when one takes a look through the telescope. The reticle was especially modified and has two sets of stadia hairs (see figure 9).

The new style Wild N3 from the other side.
Figure 2: The new style Wild N3 from the other side.
Development
The N3 was originally developed by Wild in 1926 and modernised in 1940 (becoming the other Wild N3 in my collection) and again in 1973, the one shown here.1 With the latest modernisation the tilt knob was incorporated into the parallel plate knob at the right side of the instrument (see figure 1), which made it easier for the observer to access them both. The peep sight and visor have been replaced by a cross in a telescopic sight (see figure 10).

Accuracy
The N3 is the most accurate level in my collection. It is equipped with a built-in parallel plate micrometer in front of the 42 times magnification power telescope. The instrument allows to make readings down to 0.01 millimetres, while estimating another decimal is possible. The settling accuracy of the vial is about 0.20" (0.02mm at 25 metres or 1.0mm at 1km). The instrument allowed to level a 1km double run - using the parallel plate micrometer - with an accuracy of 0.2mm (1σ, 68%).2

Notes

[1]: See the Product Overview Levels of the Virtual Archive of Wild Heerbrugg
[2]: See the N3 section of the Virtual Archive of Wild Heerbrugg

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

The Wild N3 with its original case.
Figure 3: The Wild N3 with its original case.
 
The serial indicates that the N3 was made in 1977.
Figure 4: The serial indicates that the N3 was made in 1977.

The old and new style Wild N3 compared.
Figure 5: The old and new style Wild N3 compared.
 
The Wild N3 and NK10 compared.
Figure 6: The Wild N3 and NK10 compared.

The inventory number of the previous owner Rijkswaterstaat.
Figure 7: The inventory number of the previous owner Rijkswaterstaat.
 
A view through the combined vial and micrometer microscope.
Figure 8: A view through the combined vial and micrometer microscope.

The erect view through the telescope showing the two sets of stadia hairs.
Figure 9: The erect view through the telescope showing the two sets of stadia hairs.
 
Coarse aiming is done using a seperate optical cross.
Figure 10: Coarse aiming is done using a seperate optical cross.

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