The question of whether the Einstein shift in clock rates has a bearing on the validity of the fourth Heisenberg uncertainty relation is discussed. It is shown that, even if one would accept all the relevant assumptions and conclusions of Bohr and Rosenfeld, this uncertainty relation could not be saved by an Einstein shift in the case of an electrostatic weighing. This means that the Einstein shift does not play any role in determining the validity of the fourth Heisenberg relation.