This thesis deals with the relatively unknown phenomena of longitudinal forces in conductors. A survey of relevant experiments is given. Ampere electrodynamics, which has been proposed to account for the phenomena, is compared with a Maxwell stress approach, and these are found to be equivalent. The relationship between different `action at a distance? theories is discussed. The role of relativistic electric fields, and electric fields from surface charges, is considered.
Several interesting applications such as metal punching, liquid metal pumping, water-arc jet propulsion, high current limiting and electrodynamic plasma fusion are covered, together with a novel application: the electrodynamic explosion motor.