Today completed my second stage of fermentation of wine. I checked the
hydrometer reading and it was 1.000.

Out of interest, I also checked the specific gravity of the wine with a
clinical refractometer and it read 1.033. Thinking that my refractometer
needed adjusting, I checked a distilled water reading which as it should be
was 1.000.

Why the difference in readings for a clinical refractometer and hydrometer?