The skeleton clock

I thought today it was time to give you another technical blip (actually I my decision was based on the fact that it has been a horrible, grey mizzly day and I did not fancy lingering outside taking photos.) This skeleton clock was collected today. Unusually it runs for a month on one wind, which means it runs on a dribble of power and is a sign of quality.
Used in antique spring-powered mechanical watches and clocks, a fusee is a cone-shaped pulley with a helical groove around it, wound with a cord or chain which is attached to the mainspring barrel. Fusees were used from the 15th century to the early 20th century to improve timekeeping. Springs were first employed to power clocks in the 15th century, to make them smaller and portable. These early spring-driven clocks were much less accurate than weight-driven clocks. Unlike a weight on a cord, which exerts a constant force to turn the clock's wheels, the force a spring exerts diminishes as the spring unwinds. The invention of the conical fusee was a simple advance that equalises this force. When the spring is strongest, the pull is on the narrowest part of the gear and when weakest, on the widest part of the gear, thus equalising the torque.
These gears can also be found in early pocket watches.
For those who are still awake and reading this, well done. In the unlikely information that you might want more information, the Wiki entry is here!