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A spectrometer to measure deep inelastic muon scattering needs a uniform magnetic field, in an unobstructed space of 0.8 × 0.8 × 60 m, of 2 T vertical and transverse to the long direction. Outside the field space is an iron shield used for identifying and counting of muons, for reduction of stray flux, for improving field homogeneity and also for entainment of magnetic forces. The magnet is composed of 6 m long units. Each unit is assembled by stacking 44 largely identical subunits. Each subunit is wound as a flat pancake on a window frame 1.7 × 6 m and bent into the required saddle shape. Cooling is by circulating two-phase helium through copper pipes attached to the subunits; heat transport within windings is through solid contact. Operating current, at 2 kA, is below the full stability limit. Half the magnetic forces are contained by cold tension struts connecting the two sides of the coil at top and bottom, the other half by supports between the center of the windings and the warm iron shield.