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Vol. XVII, No. 2, or this scries begins with the 1958 William M. Murray Lecture on ‘Mechanics applied to Creep Testing’ by N. J. Hoff. The lecture surveys the factors making the analysis of structures under creep conditions more difficult than under conditions where linear clastic laws are obeyed. Empirical creep laws are reviewed and the dangers of extrapolation pointed out. For complex states of stress a law is recommended based on the assumptions that principal axes of stress and strain coincide and that principal stress and strain components are in the same ratio. It is shown that slight inaccuracies in the measurement of stress, fluctuations in stress and temperature, and changes in specimen geometry, may all contribute appreciably to the scatter of test results, in addition to the effects of lattice defects and intcrcrystalline bonds. The stress distribution in redundant structures will be different under creep and clastic conditions; an analogue method for analysing the former condition, using variational principles is outlined. The problem of determining stress distribution when the condition is intermediate between fully clastic and one of steady creep, is even more difficult. Some simple examples are discussed. The final section of the paper deals with instability in the creep tensile test, and with creep buckling.