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.

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 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 The peep sight and visor have been replaced by a cross in a telescopic sight (see figure 10).

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