Abstract
The writer has theoretically inspected the results of formal investigations about permeability. As the results, it has been found that we have made the different measurement values of permeability in time, as the following three factors have never been taken care of.
(1) The errors in calculations of the measurement value.
(2) The differences due to the measurement apparatus itself.
(3) The differences by the chemical and physical changes of the porous media.
These results of the experiment had show large the differences influenced by those three factors.
