Breguet No 28 Stop-Work
The two animations below show the mainspring being unwound and wound.
Our (and God's) view of unwinding is that of the barrel rotating anti-clockwise while the arbor wheel is stationary. But the animation below is from the perspective of the barrel and the arbor wheel appears to rotate clockwise.
Our (and God's) view of winding is that shown, where the barrel is stationary while the arbor wheel is rotating anti-clockwise.
If the annulus is smaller then the mainspring will wind an extra turn. The following animation shows this, starting at the end point of the above winding animation.
Winding Small Annulus