Thomas Jefferson Clark (1869–1907), originally from New Hampshire, United States, was a lifelong friend and partner of John K. Stewart as they built the companies that would one day be the foundation of the Stewart-Warner Corporation of Chicago, Illinois.
These small automobile heaters contained coal.
The coal embers would emit heat providing some relief in a time when automobiles did not have such options.
The production of the coal needed for these heaters violated city smoke regulations and forced Stewart and Clark to build a new plant in Aberdeen, Illinois, about 25 miles west of Chicago.
[1] Clark was demonstrating the Stewart Speedometer during this rally style event when the Packard he was driving slid off the muddy road and into a ditch.