229,429. Edison Swan Electric Co., Ltd., and Price, T. W. Dec. 12, 1923. Vacuum tubes.-A refractory stem 1 of a thermionic valve is surrounded by a concentric sleeve 2 permanently secured to it so as to leave an annular space to accommodate the legs 4 of the electrode supports, and wires 5, welded or otherwise secured to the legs are folded over the edges of the sleeve and the ends twisted together. The edges of the sleeve may be notched as shown at 7 to space the legs. The sleeve is secured to the stem at a number of points.