The Gallilee clock

[ARMAND]

Strictly speaking, however, the drinking bird is indeed a perpetual system, since all things being equal, it will function in an asymptotic manner ad infinitum (if I dare say so), we would have to agree on the term, perpetual, it is not necessarily autonomous in a closed circuit or self-maintained, that means that it operates without having a foreseeable stop, otherwise its wear ... which is the case of the drinking bird or the Atmos pendulum seems ...

[Remundo]

in its strictest definition, perpetual motion is a system constantly on the move, thermodynamically isolated, from which you can draw as much energy as you want without slowing it down.

In short, perpetual motion would be an inexhaustible source of mechanical energy without "anything contributing anywhere" to maintain its vigor.

If by any trick, you manage to maintain the movement, if only to compensate for friction, you have in fact invented a thermal machine capable of converting a little heat into mechanical energy ... and you are not in movement perpetual. You are in a movement kept.

I hope everyone will understand the nuance.

[izentrop]

it means that it works without having a foreseeable stop if not its wear ... which is the case of the drinking bird or the Atmos pendulum it seems ...

in its strictest definition, perpetual motion is a constantly moving system, isolated in the thermodynamic sense, from which we can draw as much energy as we want without slowing it down.

Under a sealed bell the drinking bird stops
QED