(1) Oedometer test; (2) Limitations of the oedometer test; (3) Influence of deformation characteristics on shear strength. Stress dilatany equations; (4) Critical state theory; (5) Limitations of the critical state theory; (6) Yielding and flow in natural clay; (7) Drained tests on Bäckebol clay; (8) Residual friction in clays; (9) Drained shear strength in soft clays; (10) Comments on the tests and the test results