One possibility is to insert an infinitely variable transmission with a fusee and chain between the barrel and wheel train. Leonardo da Vinci had sketched such a design, which resembles the gearing on a bicycle, as early as the 15th century. In this system, the barrel revolves around itself and in the process winds up a chain mounted on a cone-shaped fusee. When fully wound, it pulls on the pointed end of the cone. The leverage there is at its lowest, with the result that less torque is transmitted to the wheel train. The lower the tension in the spring, the larger the leverage at the base of the fusee and thus the amount of torque delivered. Over the entire length of the process, the force transmitted to the balance remains constant.
The fusee-and-chain drive was particularly successful in large clocks. It was used on ships in marine chronometers, for example, where the need for precision was extremely high. Similar mechanisms were also used in pocket watches. However, an infinitely variable transmission requires a great deal of space, which meant that its use in wristwatches was limited.