FIG. 51 · MATEO'S MARBLE MACHINE
For Mateo
EPILOGUE · NO. 51
Turn the crank: cups lift the marbles, they zigzag down, turn a wheel and ring a bell, again and again.
MACHINE 51
MATEO'S MARBLE MACHINE
EPILOGUE
MACHINE 51
The 50 machines, and one more: Mateo’s marble machine
The 50 machines, and one more. This one is not for surviving. It is a toy for a parent and a child to build and play with together, and it is made from what earlier machines make: clay marbles from the kiln, glass marbles from the glass furnace, the climbing loop of the rope pump, a bell from the foundry, wooden parts from the pole lathe, and gears and a crank.
How it works. Turn the crank and a chain of small wooden cups lifts the marbles up one side of an upright pegboard. Each turn lifts 4 marbles 53.3 cm. At 30 turns a minute the chain moves at 15.2 cm/s, so a marble climbs in about 3.5 s. Off the top ramp it rolls at v = √(2·g·h·5/7). The marbles zigzag down, turn a wheel with five pockets, ring a bronze bell 5.5 cm across and run back along the bottom to wait for a cup. With 20 marbles, a full loop takes at least 10 s at that speed. These figures come from an ideal model that ignores friction, so real marbles run a little slower.
Mateo’s job. Every step has a task for a child: sort the marbles by colour, count the wheel’s pockets, turn the crank and count the bells.
Safety. Marbles are a choking hazard for children under 3 years: play with an adult present and keep them away from younger children. Adults do all the sawing, drilling, turning and casting.