The goniometer (or aiming circle) is like a boussole theodolite but with the difference that the reading is done on direct scales without any verniers or microscopes. It does have a micrometer to allow reading fractions. As a result it is not very accurate but much easer to read (and therefore use). The goniometer has a compass that is used to align it with magnetic north which allows measuring magnetic azimuths directly. The compass needle can indicate other directions (it is swining freely) but there is no compass card attached to the needle to allow reading. The device has a scale in (NATO) mils (6400 to a degree, or around 1 milliradian per division).

The instrument came together with the dome. The bottom part of the dome which is separate in most Wild Heerbrugg theodolites is in this case, as with the T0, part of the base plate of the instrument. The instrument also came with two yellow filters to dim the light. For use at night there is a small, red, light which has an adjustable slit. The lamp is fed from a (small) batterybox. Finally, there is another light which can be used as a flashlight and which is run from a separate batterybox. Everything was mounted in a wooden crate lined with foam making the whole setup very secure against shocks.

The box shows text in German as well as French while the batteryboxes are stamped with a square cross. All in all this was probably originally a Swiss instrument. How it ever came to be in the US is unknown to me. The instrument has been painted over and given the number 286. The original serial number (1347) is engraved and still showing underneath the paint togehter with the manufacturers name.

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