Field Mill Electrometer (JCI 131 FM): A compact and robust instrument for continuous long term measurements of the ambient electric field, adverse environmental conditions. It is particularly suitable for continuous monitoring of atmospheric electric field conditions, associated with varying weather conditions and electric content, such as during thunderstorms or extreme volcanic activity. The output signal is proportionate to the electric field strength and currently operates at a range of 2kV/m with a precision better than 1%. The instrument is mounted on a 3m mast in order to avoid ground distortions. The FM is ideal for remote site installation due to its low power consumption and straightforward data collection system.