Fun with Physics, the simplest steam engine.

I like black tea with lemon and brown sugar.
I like hot black tea, thus when I drop the tea bag into the very hot water
I place a saucer onto the cup to hold in the steam.
That way after lemon and sugar and stirring it’s still a nice hot cup of strong black tea.
Usually I simply place the saucer right side up, today for whatever reason I flipped the saucer upside down onto the cup
for the minutes I let it steep.
I go off to deal with something else, then start hearing this weird tapping noise.
It takes a moment but I get back to the cup soon enough to see it in action.
It’s still hot enough to see the glass saucer pop up a fraction of an inch, to allow the built up steam pressure to escape, then smack it drops back to the rim. By now my gal breaks my trance, asking: what’s that noise.
"It’s the world’s simplest steam engine honey - I just made James Watts’ childhood discovery.
As they say chance favors the prepared mind.
My lesson, when I place the saucer right side up there’s no seal, the steam escapes.
Placing the saucer upside down creates an anticline that traps steam
and creates a flexible seal
even as the lid raises a couple fractions before finally breaking the molecular bonding
and escaping.
Fascinating stuff all around me, rediscovering old discoveries is the spice of life.