It is a winter morning at Blue Heron Orchard, and our small community is making apple butter — owner Dan, his wife, a couple of kids. A neighbor stops by, a friend joins us later. We sort and wash the apples, tossing aside some, cutting out bad parts of others. The Red Delicious are big this year, juicy. The Winesaps are always smaller, but they are hardy and healthy; they are also the last ones that came off the trees. Galas are an earlier apple, they are softer by the winter, losing some of their crispness. It takes more work to clean them. ​ Next, we take the washed apples to the manual grinding machine. The kids load the apples from the trays into the hopper, a handful at a time, making sure there is a continuous flow from tray to grinder to bin. Across from them, one of us is turning the wheel of the machine. Keeping a steady rhythm helps, because it is going to take some time to crunch all the apples we need for the butter we are making, over one hundred jars. ​ Galas are a breeze to grind. It takes little pressure of the teeth of the machine to crunch these softer, medium-sized apples. The first bin is full, and now comes a tray of Red Delicious. The kids are doing well, even though the apples are so big they can only pick up one at a time. ​ The wheels of the machine are spinning towards each other, but the teeth of the grinder have no hold — the apples keep bouncing up and falling back down, not getting caught. Dan keeps moving the turning handle and asks the kids to load more apples to prevent the bouncing. With more apples in the hopper, we hear the juicy fruit getting crushed, one after the other. Every time one gets caught between the teeth, Dan feels resistance at the turning wheel. He keeps going, and once he reaches a good speed, the jerking motion stops — the flywheel is now stabilizing the movement by releasing energy just when it is needed. ​ With the Red Delicious all done, lots of tough little Winesaps wait their turn on the next tray. They are not easy to work with, but we would never leave them out of the butter — this variety gives the Blue Heron Orchard products a distinct flavor you can recognize instantly. The kids are loading, Dan is turning, and the flywheel does what it is designed to do, releasing energy into the system when an especially tough apple needs more pressure. For much of the time when the grinding machine is in motion, it seems like the flywheel is nothing but extra weight, making it harder to turn the wheels instead of helping. Its role of stabilizing the rotary motion becomes evident, however, when that bit of extra energy is needed.