Tuesday, March 13, 2012

Pythagorean cups

I am pleased to report major developments in the Geek Lab: we re-engineered the Pythagorean Cup! Also known as the Cup of Tantalus, the Pythagorean cup punishes gluttony. Fill the cup a modest amount, and the drinker may consume the beverage in peace; overfill it, and it siphons all of its contents into the drinker's lap.

My 2012 Session 1 Claymakers "Pottery for Geeks" class mostly eagerly took on the redesign of the Pythagorean cup. I made a simplified test model, based on this image from Wikipedia:
A hole at the base of the central cap allows the cap to fill as the cup fills. Once the liquid reaches the top edge of the inner pipe, it flows down through the center of the cup. Because of the cap, the outflowing liquid can only be replaced by more liquid, not by air, and the entire contents of the cup siphon out.

The test model worked extremely well, but several of us opined that the big round thang in the middle was unsightly and would arouse gluttons' suspicions.

After some geek conferencing, we decided to incorporate the siphon into the handle. I threw a few thin tori and kluged them into siphons. In the image below, the cup on the left siphons its contents from the cup into the inner torus, up into the outer torus, and out the bottom of the handle. The cup on the right siphons from the cup into the front torus, up into the back torus, and out the bottom.
Aside from the handles looking clunky, it took significant effort to align, seal, and disguise the holes between the torus segments, and neither handle siphoned particularly well: both lacked sufficient water pressure for a satisfying drainage rate, and the curved handles sent water dribbling onto the undersides of the cups rather than straight down--that's Newton's first law for you. While Acme Klein Bottle sells a cup that siphons efficiently through its handle, these torus-handle models are duds.

The next design merely shifted Pythagoras's unsightly siphon from the center of the cup to the edge. The siphon was significantly easier to build than the torus handles, but remained unsightly. I attempted to distract the glutton's eye by covering the outside of the cup with tessellating lizards and positioning a lizard over the siphon, taking inspiration from Escher's Reptiles (1943).
Wanting to further minimize the obtrusiveness of the siphon, I explored a final siphon experiment modeled on Acme Klein Bottle's Tantalus wine glass. The handbuilt, relatively small siphon was trivially easy to build, although the frog decoy perched upon it took a while to make.
The lizard cup beat the frog: excellent water pressure made for smooth and rapid decanting. I suppose the frog cup might function acceptably during a gluttony emergency, but insufficient water pressure makes for a halfhearted dribble. With further tinkering--for example, making the inflow side of the siphon wider than the outflow side--the simple siphon* might yet prove worthy of replication.

Always the rebel, Schroeder Cat managed to drink out of the bottom of the cup.

*Simple siphon met a python
Going to the fair;
Said simple siphon to the python,
"Will you drink my ware?"
Said the python to simple siphon,
"You've poured one drink too many";
Said simple siphon to the python,
"But look, I have not any!"


Bernadette said...

OK, now I am envious because it sounds like you are having too much fun!

Anonymous said...

I have been working on greedy cups for several years and have finally gotten one which looks like a normal cup. Would love to share ideas and pictures. Im in California and on facebook. Possible to exchange email addresses on facebook??
Don Yost