An arithmetical correction. I forgot to divide by Pi.

The resistance of a hemispherical electrode, 9 inches diameter, in
salt sea water, is even smaller. It is only 0.32 ohms.

Incidentally. the resistance of a flat circular disk of diameter D
metres, in contact with the soil surface, is given by :

R = S / 2 / D ohms,

where S = soil resistivity in ohm-metres.

In sea water, a disk of 12 inches diameter has a resistance of 0.37
ohms. Which is negligible in comparison with the radiation resistance
of a 1/4-wave vertical antenna of 36 ohms.

Careful readers should make a note of these hints and tips, free to
USA citizens, in their notebooks.

My own notebooks extend from volumes A to letter S. I'm wondering who
to leave them to in my Will & Last Testament.
----
Reg, G4FGQ.