Foot warmer device from 1918. It is pretty cool!
On February 1, 1918, Halls Etheridge filed a patent for a unique device to warm users feet. The device includes a cylinder in the heel portion of the shoe.
A piston compresses air in the cylinder when user presses the foot down.
The compression heats up the air, which is then expelled into the shoes.
The device is operated solely by the motion of walking. The device is simple and inexpensive, yet will be highly efficient for the purposes intended. We prefer the mechanical foot warmer from 1918, than the battery powered insole foot warmers availble now – http://ecx.images-amazon.com/images/I/61AHxl3OOTL._SL1001_.jpg
Patent Information
Publication number: US1272931 A
Patent Title: Foot-warmer
Publication type: Grant
Publication date: 16 Jul 1918
Filing date: 1 Feb 1918
Priority date: 1 Feb 1918
Inventors: Halls B Etheridge
Original Assignee: Halls B Etheridge