This machine accomplishes energy conversion through the electromechanical coupling implicit when a rotor-stator capacitance varies periodically as the shaft turns. It has the potential for low cost of manufacture and high efficiency. Although the principle of operation has been known for a century and various models have been built, a practical machine, competitive with the conventional magnetic machine, has yet to appear. All attempts have led to machines much larger than the conventional rotating machine. The power density of a varying-capacitance machine is proportional to the energy density in the rotor-stator gap, which in air - or even in vacuum - is comparatively low. In the proposed machine, a solid dielectric is introduced into the working gap, together with a thin layer of air or vacuum@ and this is made practical through a novel arrangement of rotor and stator. Preliminary calculations indicate that a great increase in power density should result from these innovations. It is proposed to build an apparatus to test these ideas and demonstrate the feasibility of this new machine. If successful, this should lead to a new type of machine, lighter, more efficient, and lower in cost than conventional alternatives.The potential commercial application as described by the awardee: Research will lead to the development of rotating electrical machines such as motors, generators, and alternators for AC or DC power. The scope of application could include the complete range of machine ratings, from large, synchronous machines for power systems, through fractional hp sizes, to miniature machines. Advantages are low cost, efficiency, and light weight.