The parallel-plate Townsend discharge triggered by a flash of ultraviolet light on the cathode gives a current to the anode which depends strongly on the value of γ, the number of new electrons liberated from the cathode per positive-ion impact. An expression is derived relating γ to the first Townsend coefficient for ionization by electrons α and the anode-cathode separation X, which provides an easy experimental procedure for arriving at γ. Measurements are then given for γ as a function of Ep, the ratio of field strength to pressure, for Ne, A, and Kr on a freshly cleaned Mo cathode. The values of γ are essentially independent of Ep above 175 volts/(cm×mm Hg) with values of 0.20 for Ne+, 0.083 for A+, and 0.053 for Kr+. At lower values of Ep, γ decreases toward zero, but this decline is probably related to the back diffusion of electrons to the cathode and does not represent a decrease in the basic γ process. With A+ ions and a nickel cathode coated with activated BaCO3, the value of γ also leveled off at higher Ep at a γ value related to the degree of activation of the BaCO3. Significantly, the value of γ for this surface did not tend toward zero at zero Ep. This may be attributed to a different distribution of electron velocities for the ejected electrons from the coated surface than for the pure surface.