Perpetual motion machine
From Jenny Everywhere Wiki
Three perpetual motion machines were among the exhibits of the Jenny Everywhere Museum in the Strange and Wonderful House. (PROSE: Our Strange and Wonderful House: The Jenny Everywhere Museum)
A broken “Carnot-engine” perpetual motion machine was one of the items accumulated in the closet of Jenny's apartment in one universe. When she and Kim went through the closet to sort its contents, they found it again. Jenny reflected that she could repair it if she found the right parts, and they set it aside to use it as a birthday present for Professor Awesome. (PROSE: Cleaning Day)