Carrier (angle meter)
Model 554
Description
Carrier (angle meter).
Additions
The model is to be classified into the time before the French Revolution (as indicated by the Fleur-de-lys as a symbol of the French king).
Marked on the circle are the angular degrees from $1$ to $360$.
In the initial state both rulers of the model are closed, so that they are lying exactly on top of each other. To measure an angle or to draw an angle of a specific size the upper edge of the rulers has to lie on the $0^\circ$-point. Now the upper ruler is moved (it turns on top of the circle) until the lower edge is lying on top of the angle to be measured or the desired number of degrees on the circle is reached.
Today there are similar instruments in use, e.g. during the building of houses or in medicine to measure bones.
Showcase of this model is Case number 45
References
Adams, G.(1985). Geometrische und graphische Versuche oder Beschreibung der mathematischen Instrumente, denen man sich in der Geometrie, [...] und in der Perspektive bedient, Nach der Deutschen Ausgabe von 1795, wissenschaftliche Buchgesellschaft , Darmstadt.