Warren S. Johnson, a self-taught individual who worked as a printer, surveyor, teacher, and school director, filed U.S. patent 281,884 on July 24, 1883, titled Electric tele-thermoscope. The device connected a metal thermometer to an electrical circuit, allowing the temperature of a room to trigger a signal directed to the janitor of a school in Whitewater, Wisconsin. The signal was intended to eliminate the need for the janitor to conduct hourly rounds to adjust manual valves near the furnaces, which were installed in the basement and heated the classrooms. The National Inventors Hall of Fame, which inducted Johnson in 2018, described the device as inefficient but acknowledged its role in the development of the building control industry. The patent document described a thermostatic transmitter that sent information rather than displaying it. It included a formula from the time in which Johnson presented himself as a resident of Whitewater, Walworth County, State of Wisconsin. The patent protected the association of a metal thermometer with an oscillating balance equipped with contact points and springs, designed to close electrical circuits. The deformation of the metal due to heat caused the balance to oscillate, and this movement closed one or another circuit. The title itself indicated the device's function: "tele" from Greek for "far," meaning the thermoscope read the temperature at a distance. Regarding the exact form of the signal, accounts diverge. Some mention a bell, others a room-specific indicator that would display "hot" or "cold." The principle, however, left no doubt: the temperature of the room commanded the sending of the signal. The janitor remained in control, as the 1883 device eliminated the hourly rounds but the final decision remained human, notes the Hall of Fame. Johnson later combined compressed air and electricity to automate valves and dampers, transforming the thermostat from a messenger into an issuer of orders. He left teaching in 1883 and in 1895 presented the first fairly complete multi-zone automatic system for widespread distribution. This system was found in offices and schools, as well as in the U.S. Capitol, the Smithsonian, the New York Stock Exchange, West Point, and at Andrew Carnegie's. The Hall of Fame sees this as the origin of a building control industry that today amounts to billions of dollars. Patent 281,884 already anticipated the adjustment of setpoints: a claim covered an indicator arm associated with a screw and an adjustment wheel of the thermometer. One hundred forty-three years later, the gesture of adjusting a thermostat remains the same, with only the distance between the room and the one who obeys having changed. The thermostat compares the measured temperature to the one requested and sends an order, similar to how the Whitewater balance functioned. The knob sets a threshold, not a power: in an installation that works on an all-or-nothing basis, turning it all the way would not speed up the temperature rise, it would only delay the shutdown order. It is better to choose a reasonable setpoint and let the system work.