Instrument	:	Equerre
Manufacturer	:	Unknown
Country of origin	:	Belgium or The Netherlands
Manufacturing year	:	Late 19th, early 20th century

In my collection since 2005 is this instrument which is the predecessor of the modern optical square. It is quite a bit younger and much simpler than the surveyor's cross in my collection. The instrument is divided in 8 directions with corresponding visors, four of which have horse hairs as reticle. The advantage over the surveyor's cross is that all directions are fixed while the surveyors cross can only be fixated at 90°. This type of visor with horse hair can also be found on a graphometer, while the others can be found on the before mentioned surveyor's cross.

The compass shows the directions of the winds as 'N', 'O', 'Z' and 'W' (Noord, Oost, Zuid and West, in English: North, East, South and West), indicating that the instrument was intended for the Dutch market. The handle has a conic hole, to make it possible to attach the instrument to a tripod (similar to the one of the graphometer) or staff.