At times an invented device may not be useful during it's initial stages but as time passes the utility of the device may become apparent or the device may be used for a very different purpose. One such device is treadmill, an important equipment of the modern day gym was actually used for punishing prisoners during the 1800s. Treadmills were invented in 1818 by an English engineer named Sir William Cubitt. Initial treadmills had a mechanism different from the present day treadmills, requiring the user to step upwards like walking up an endless staircase.
The prisoners were made to turn a large paddlewheel by stepping on the spokes of the machine. Turning the wheel would in turn pump out water, crush grain, produce electricity, power ventilators in mines etc. Prisoners were often forced to spend up to six hours a day on the wheel in order to utilize their muscle power, to cure their idleness and to do useful work, this was equivalent of climbing about 5,000 to 14,000 feet. So the treadmill was used to torture and punish criminals. They remained in use to punish prisoners until the second half of the 19th century but later they were used to diagnose heart and lung disease in hospitals and they gradually turned into exercise equipment. Treadmills today are used for various purposes like medical facilities (hospitals, rehabilitation centers, medical and physiotherapy clinics, institutes of higher education), sports clubs, Biomechanics Institute, orthopedic shoe shops, running shops, Olympic training centers, universities, fire-training centers, NASA, test facilities and training rooms of police and army, gyms and even home users.