A model magnet has been constructed to study the behavior of a large superconducting coil on an iron yoke at room temperature. The coil, wound with niobium stannide ribbon, has an average diameter of 40 cm, a maximum excitation of 5×105ampere‐turns, and a stored energy of 85 kJ. The superconductor carries the same current, 120 A, on the pole and yoke as it did when removed from all iron. Nylon spacers served as compression members of low thermal conductivity to support the 18 000 kg magnetic force.