A RESEARCH and Development Lecture, arranged by the Royal Institution and the British Science Guild, was given by Mr. Clifford C. Paterson, director of the Research Laboratories of the General Electric Company, Wembley, on November 21, at the Royal Institution. After the work of J. J. Thomson, electricity could be thought of in terms of the in dividual electron, its habits and affinities. One of the two main reasons for the practical usefulness of electricity is its ease of control. The other is its transportability. It is in the direction of the control of electricity that the free electron has of late given the engineer new and extraordinary powers. The secret of the revolution is that electricity can now be freed from conductors. A stream of free electrons, whether in a vacuum or a gas, can be manipulated with such facility that the electricity can be increased or decreased at the rate of millions of times a second, or alternatively as slowly as desired, and no limit is set to the amount of energy which can be so controlled. It was the object of the first part of the lecture to explain and to demonstrate why these extremely rapid actions of the electrons are wanted. So much of what the eye sees and the ear hears consists, if analysed, of extremely rapid happenings. The eye and the ear are unconscious of these high speed fluctuations and vibrations although sensitive to them. In order that these very rapid oscillations and variations may be faithfully reproduced and transmitted it is necessary to make exact electrical copies of them. This is done by suitably controlling a stream of free electrons.