: How did watches work before batteries?
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Tension coils that acted like a slowly releasing spring that drive the movement (mechanism) of the watches. Winding the watch stored energy in the coil and could typically run for a few days per wind.
Some had incredible levels of accuracy given the limitations of the technology.
Springs. Have you ever heard of someone “winding” their watch? That refers to turning a little knob which tightens a spring. The spring pushes on stuff, and that pushing force turns the gears that make the watch work.
Watches worked by stored energy in a wind up spring. Self winding watches had a mech that would wind the spring just by your normal wrist movement during the day. Pretty sure wind up watches are still made.
Springs and gears. You would have to wind up the watch spring with a little key or knob and set it before it would work, and then it would keep time for several hours, a day, maybe even longer depending on the watch.
Springs! You would have to wind your watch to keep it working. I’m not a horologist but there would be a spirally wound spring connected to gears that would spin at the correct speed to keep the watch displaying the correct time. Every so often you’d have to wind up the spring like you wind up those little toy cars that drive across the floor.
The same way many still work today… they get manually wound, and the energy stored in a spring powered them. There are also watches that have pendulums inside that use the wearer’s motion to wind the spring. This is how the high end multi-thousand dollar watches — usually advertised as automatic — are made today.
A wound-up mainspring drives an escapement, which drives an oscillator.
A mainspring is simply a spiral of metal, which is wound by twisting the center or outside and so coiling it more tightly. This is what provides energy to the watch, and typically will be hooked up through gears to the hands of the watch. As such, the unwinding of this spring is what moves the watch hands.
The escapement prevents the spring from just spinning freely and unwinding. It is combined with the oscillator – it gives the oscillator a push to keep it going, and in turn the oscillator ‘tells it’ when to move forward. The oscillator keeps time, the spring keeps things moving, and the escapement is the bridge between the two.
This makes more sense with an animation, so [here](https://upload.wikimedia.org/wikipedia/commons/a/a7/Anchor_escapement_animation_315x478px.gif) is an animation. This is the escapement for a pendulum clock, but it is conceptually the same. The mainspring drives the big spiky wheel (in a pendulum clock the spring is usually replaced with a weight), and the pendulum swings side to side as the oscillator to keep time.
In a watch, the oscillator is a weight on a spring, bouncing back and forth (typically, a weighted wheel, spinning back and forth), so that it does not rely on gravity.
Edit: minor correction for terminology
The development of watches was a fascinating important process. An accurate timepiece was necessary to know a ships position east/west. So the British, the world wide maritime empire, had a contest to develop an accurate watch that would work in a ship. Then they tried to cheat John Harrison, the man who did it. There is a great book, *The Watch*, that covers this
They are not as expensive as some let on. Some of the luxury brands can get up there of course. But an antique store find will get you a decent ’60s-90s watch for under $100 that just needs a bit of TLC. I rotate between my mechanical and the newer ways of ‘how watches work without batteries’, a Casio Eco drive. The Eco Drive uses light/power cells. Had the current one for 5 years and still tickin. Timex has a ‘solar power’ expedition north watch in the pipeline as well.
https://youtube.com/c/WristwatchRevival
This YouTuber takes apart, cleans, repairs, and reassembles watches. I find it soothing to watch and he does a great job of explaining how it all works.
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