Honest John wrote
Rod Speed wrote
Honest John wrote
wrote

whatever those "t's" mean.

Those Ts simply refer to the luminous substance used in the watch to
make the hands and dots "glow in the dark". I believe the Ts stand
for Tritium, the amount of Tritium used is above a certain industry
established limit for this slightly radioactive substance.

Tritium is a radioactive isotope of hydrogen, the one after deuterium.

Unlikely that thats in a watch to make the hands glow.

Then what substance is in "Tritium tubes" that make
several makes of watches hands glow ????

Those are actually glass vials, and it isnt
really that practical to do the 'dots' that way.