Instrument	:	Graphometer (half circle)
Manufacturer	:	Unknown
Country of origin	:	France
Manufacturing year	:	Second half 19th century

In my collection since 2005 is this instrument which is the predecessor of the transit. The instrument is divided in half degrees with complementairy annotation on the circle (0 - 180 and 180 - 0 degrees).

Invented in 1597 by Frenchman Philippe Danfrie, instruments like these have been used for land surveying since the late 16th century until the late 19th and possibly early 20th century. The alidade has two verniers reading 30 minutes. Observations can be read up to one minute and estimated up to half a minute.

The compass is divided in 360 degrees at whole degrees. The visors are equipped with copper wires, but I'm not sure if this is original, it could be that these wires should be made of horse hair like in an equerre.

The instrument has no markings at all, but a similar instrument with signature by Eugène Ducretet (and as Ducretet was the French radio pioneer this could explain the copper wires) can be found on this site.
This could either mean that Ducretet build both instruments, but never signed the one I own (which I think is quite unlikely), or that Ducretet modified a graphometer (by adding the level) build by the same firm or person as mine and than signed it. The latter means that the instruments were not made by Ducretet at all, but that he signed the one he modified. If anyone knows the answer to this, please let me know.
The handle has a conic hole, to make it possible to attach the instrument to a tripod or staff. The handle is equipped with a ball bearing that allows the instrument to be adjusted horizontally.