Abstract :
THE USUAL TYPE of powered vehicle requires a material medium upon which the vehicle exerts its thrust or traction. Thus the locomotive pushes back on its track; the propeller-driven airplane pushes back upon the surrounding atmosphere; even the jet-airplane or rocket pushes back on the discharged gases. In this essay is described a means of propulsion which does not require any material medium upon which the propelling thrust is exerted. It will be suitable, therefore, for driving space ships in interplanetary or interstellar journies and I earnestly call it to the attention of promoters and investors who contemplate entering into this virgin field of activity.
