Drinking Bird
Safety Warnings
Warning: Volatile Liquid Contents
Purpose
Evaporative cooling of the bird's wet head lowers the vapor pressure of the ether inside, drawing liquid up into the head and shifting the center of mass until the bird tips forward to "drink." Demonstrates how small temperature differences drive vapor pressure changes and mechanical motion.
Figure 1:
The drinking bird in operation, captured with motion blur showing the rocking cycle. The bird has a white body, red base, blue hat, red beak, and green tail feather.
Figure 2:
The drinking bird enclosed in the plexiglass case with beaker. Covering the bird allows humidity to saturate, stopping evaporation and halting the cycle.