It has been found possible to draw currents of the order of several thousand amperes from cold metals by field emission in vacuum. This principle has been put to use in the design of a condenser discharge x‐ray tube for high speed radiography. An auxiliary electrode spaced close to the cathode and connected to the anode through a high resistance serves to initiate the discharge which is then transferred to the anode. This auxiliary electrode is made in the form of a focusing electrode. Radiographs of bullets and the internal workings of other high speed objects are now made possible.