This probably is not the rarest Wild Heerbrugg instrument in my collection. Or at least not in terms of amount produced. However, there don't seem to be many around of these, it being the archetype of the most accurate level produced by Wild. Where the second generation is abundant (especially in the USA), the first ánd third (last) generation are not seen that often. So when one came up for sale, I hesitated for about 30 seconds before I bought it... Those 30 seconds were to verify it was a first generation and complete (enough) to warrant the price asked for it.

The instrument is actually almost complete (the plumb bob is missing) with original case and original paint. It has seen use but is in generally good condition for its 80 years of service. This particular instrument was produced prior to 1931 (probably around 1929 or so) and is from around the same time as my archetype T2 theodolite.

What makes this instrument different from its later model is that all the parts are 'exposed' to see. What is special is the (separate) parallel plate micrometer attachment. Where on later N3 levels the parallel plate is part of the instrument, on this one it is detached (otherwise it does not fit in its case). Separate plan parallel micrometers are nothing strange with levels but usually they are an attachment to make a less accurate level better. This level is however designed as being highly accurate with a tilting index. a long bubble level and even adjustment screws on the tribach that can be to revolve with a greater resistance (keeping them in place against involuntary momvement). So having a separate plan parallel plate seems a bit strange. It does however make for very compact storage (in a case screwed open / close with a triangular key).

The arrangement for attaching the plan parallel plate is quite clever. To ensure accuracy the system is set up in such a way that it always comes back to the same orientation and is kept in place with a tight fitting screw. The plan parallel plate is rotated by a slot that fits exactly in a ball joint on the instrument and is 'rotated' on that joint. The rotation also positions the screw in the right place. When not in use the parallel plate is stored in the box on top of felt pedestal locked by a metal bar so that it cannot shift or get damaged.