An apparatus is described which provides a simple means of obtaining stirring or pumping action in a pressurized system. Since no packing glands are employed, the device is leak‐proof. The required mechanical action is provided by reciprocating motion of a soft‐iron armature enclosed in the system and driven by a pair of electromagnetic coils. Input to the coils is provided by a thyratron‐controlled circuit. The circuit and constructional details are given.