The Thimble Steam Engine is a 1/16 inch boar 1/16 inch stroke oscillating steam engine designed by Dr. J.R. Senft presented in Live Steam magazine, October 1976. (Engine is on top).
The scale of the engine can be seen by the US dime sitting next to the engine stand. At the bottom is a miniature alcohol lamp. The lamp heats water contained in the capped brass sewing thimble supported by the ring and three legs. Screwed into the top of the thimble is the engine itself. Once steam pressure is achieved the flywheel can be spun to bring the engine to life. The engine runs very fast with a sound reminiscent of a mosquito. Due to the small volume of water the engine will only run for less than a minute. It runs more successfully on about 15 pounds of air pressure using a separate adapter and stand.