Not all types of heat engines are suitable for practical application. Some of them can be used only for demonstration of the interesting physical phenomena. One of such engines uses the loss phenomenon ferromagnetic material of ability to be magnetized when heating to temperature exceeding Curie's point.
1. Take the smallest magnet from rare-earth alloy which you will be able only to find. Handle with such magnet with care as it is so strong that it is capable to cause a trauma. Consider, however, that during this experience it completely will degauss. Therefore use such magnet which is not a pity for spoiling. In it there has to be an opening.
2. Make the basis of a swing pendulums of a steel wire. To use for this purpose a tree as on an illustration, it is not recommended as it is fuel. On this basis suspend a magnet, having passed through an opening in it a wire is thinner, and surely copper.
3. Sideways fix a big usual weak magnet so that small rare-earth to it it was attracted. The pendulum deviation corner with a small magnet from a vertical axis has to be absolutely small - insufficient in order that the small magnet when the pendulum comes to vertical position, could not be attracted by a big magnet, but sufficient in order that it every time to fall into this state of the pendulum out of a candle flame.
4. Put the lit candle under a rare-earth magnet. Be careful at treatment of her. When she warms it up to the temperature exceeding Curie's point that not only will degauss, but also will lose ability to be attracted by a big magnet. The pendulum will accept vertical position, and the magnet will appear out of a flame and will begin to cool down. When it cools down, though will not be magnetized, but again will gain ability to be attracted by a big magnet. Having attracted, it will appear over a candle flame, and the cycle will be repeated. Fluctuations of the pendulum will continue until not to remove a candle, or it will not burn down.
5. In this experience not the residual magnetization of a small magnet, and its ability to be attracted is important. Though the first of these its properties will be lost forever during the first moments of experience, the second will be restored every time when the magnet is out of a flame. It means that with the same small magnet it is possible to repeat this experiment unlimited number of times.