hawker typhoon turn and slip indicator graduation

[EMS_Golden_Rabbit]

Hello,
I would like to know what the bottom needle measures on the  turn and slip indicator of the hawker typhoon.

Thanks

[EMS_Kurtis_VR]

The bottom needle of the instrument measures the rate of turn (yaw rate), indicating how quickly the aircraft is changing heading — typically marked for a standard rate turn of 3 degrees per second or 180 degrees per minute (useful tip for calculating the time needed for a hippodrome).