Like more in my collection this is a former Rijkswaterstaat sextant; this time one that did service around the Wadden island of Texel. The instrument is marked '8' and came with a diagram for the 'Foksdiep'; a small trench between Texel and Vlieland. The instrument itself is (much) older than my other Rijkswaterstaat instruments; coming from 1935. The instrument is a geodetic sextant (400g) and has a slot for taking a prism which unfortunately is not present. The original filter is still present wrapped in a piece of paper showing 'Shell - 's Gravenhage'. 

There are a few details that make this instrument stand apart from the other de Koningh survey sextants. One is ofcourse its 400g division. Not very uncommon it joins a select few others in my collection. What makes this one special is the inclusion of a parallax table rather than a correction table. Where a sextant would normally have a calibration certificate stating the graduation errors; this one gives the correction for measuring towards objects that are closeby. Much handier as most instruments by mid-century would be stating 'this instrument is free of corrections for normal use'. Something else none of my other sextants have, is a rotating handle which can be folded flat down for storage.

The most special is the canvas carrying bag however. When I bought the instrument this was not mentioned so it was a nice surprise. The carrying bag was loose but two holes in the front obviously showed it had been around the box on a regular basis, protecting the box. The leather straps have broken but otherwise it is in good shape, showing the transport labels 'Fijn Instrument - Voorzichting' and 'Delft'. This label is also found on other instruments and originates with the survey department of Rijkswaterstaat.