In triaxial tests with lubricated enlarged end platens on sand, the internal displacements have been measured using lead shots and x-ray technique. The strain distribution so obtained confirms the homogeneity of deformations. A comparison of the axial strain distribution over the height of the sample obtained with x-ray technique and from surface measurements using a precision theodolite revealed that the much simpler method of surface measurements can be used as a criterion for homogeneity of deformations.In addition a comparison of the volume changes measured using the more accurate x-ray technique and the simpler girth-gauges showed that even the most carefully made girth gauges will underestimate the volume increase and as such are to be used with caution.