Watchismo's got the news on Puja's 1940 Thermo-Pneumatic Clock — a time-keeping apparatus like no other:
"At the lower left, shielded by a translucent housing, is a carbon rod resistance that heats the colored alcohol in the glass vessel just above it. This causes some of the alcohol to vaporize, the pressure pushing the liquid up the connecting pipe to the vessel at top right. As the latter gets heavier the wheel bearing the four vessels experiences a torque that rewinds a remontoire spring driving a conventional gear train and escapement. This clock has a pendulum-controlled escapement, but models with balance wheel escapements also existed."
1940 Puja Thermo-Pneumatic Clock
