The general scope of the paper covers the present day commercial tube; states the methods of design; and gives the general dimensions. It later brings forth an entirely new method for obtaining electron emission and control. This new method of heating provides means for heating sheets or discs of tungsten or other high temperature metals to incandescence, which sheets or discs are enclosed in evacuated vessels or ones containing gas. The tubes in which the grids are made the inductor to heat the cathode provide a radio frequency method for shutting off the current twice per cycle, and gives a double frequency in the output circuit. By these new methods set forth in the paper, it is evident that the tube engineering art will be greatly benefited.