The seal Edward used throughout most of his career combined the Japanese symbols for Earth and Fire.
You will also be able to identify all three of his initials T.E.H.
The seal was usually applied to the underside of his pieces and depending on the glaze used were sometimes difficult to spot.
When at school, Edward's pieces were marked with his initials and the class name that he was in at the time.
His work at University was rarely marked and as such can be readily identified as made during that period.
An early version of the mark merging his initials was rather crude.