The parameters of the specific-risk-of-fracture function of Weibull were determined for glass cylinders subjected to flexure. The total probability of fracture was used considering the maximum stress of fracture, and considering also the location of fracture. Weibull's parameter m obtained by means of both procedures is in keeping with theory and it amounts to m = 7.5. In addition, the dispersion of Weibull's parameters was studied using the inversion of Fisher's information matrix, whose values showed a correct execution of testing. Moreover, the distribution of fracture time during testing was investigated, and neither fracture stresses nor location thereof exhibited whatever influence attributable to this time.