The annealing behaviour of a series of technical flat glasses of known composition was examined. The glasses were mechanically strained, and the decrease in birefringence at various temperatures with time was followed as in the experiments of Adams and Williamson. The half time value, th, was determined for various temperatures, which is the time required fro an initial strain corresponding to a birefringence of 100mu to drop to half this value. The temperature dependence is then given by the relationship o=-K.log tn + C, where O is the temperature of the experiment ,K is a constant which is a measure of the "length" of the glass and C is also a constant, representing the temperature at which the half time is one second. After the annealing characteristics of this series of glasses were established the influence of various factors of importance in the rapid annealing of glasses was investigated in more detail using one of these glasses.
