The sight drops through a socket in a pivoted bracket which is provided From Treatise on Service Ordnance.
These coils are placed with their axes at right angles to one another, and at the point where the axes intersect a small pivoted needle of soft iron is placed, carrying a longer index needle moving over a scale.
With that, he pivoted on one heal and walked away.
In the other gap are pivoted two coils wound on an iron core and connected at nearly a right angle to each other.
The Arab traders in the Levant certainly used a floating compass, as did the Italians before the introduction of the pivoted needle; the magnetized piece of iron being floated upon a small raft of cork or reeds in a bowl of water.