| Brand | Unbranded |
|---|---|
| MPN | Xii |
Check the listing for details. Architect Or Surveyors Pocket Cross Or Optical Square. Brass Antique. Condition: Used. Listed at 233.71 USD. This is a beautifully made unbranded pocket device for determining a 90 degree angle. It was clearly made by a craftsman in a small batch with the two halves numbered xII. There are three fine adjustments via square headed nubs. The case is rotated to the working position and you sight through the small hole . Rotating the top back closes the apertures. The outside is in very good condition - not perfect - see photos. The age is revealed inside by the aging of the blacking and deterioration of the mirror silvering- the 90 degree reflection is very poor. I suspect around 1870’s but let me know if you know better. It’s similar to the much more common pocket sextants, but much rarer. A great collectable.
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