Two circuits for the regulation of temperature by means of a bridge‐controlled thyratron are described. The first utilizes a resistance thermometer; the second controls through changes in the resistance of the furnace winding. Improved stability is achieved by adequate filtering of the voltage applied to the control grid of the thyratron. The circuits are so designed that extreme overload in control voltage never causes erratic behavior; thus when the thermostatic bridge is set for a new temperature, unstable operation does not occur, and control is established smoothly and promptly.