A new constant tensile stress creep testing machine is described. The machine makes it possible to keep the stress constant within 0.1% up to a strain 0.45, assuming the volume of the specimen does not change during the test. The cam profile has been solved for specimen gage lengths of 50.0, 35.0, and 25.0 mm. The static counterbalance of the loading system ensures its high sensitivity, which, together with the minimizing of frictional forces, offers the possibility for the tensile stress to be accurately defined. Erratum to this paper appears in 4(4)