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The equations governing the free-surface flow of a tubular film of liquid are derived from physical arguments, which throw some light on the formal process described in part 1. The solutions of the equations are discussed, in particular with reference to the film-blowing process for the manufacture of thin sheets of thermoplastic material. The qualitative adequacy of a model based on the dominance of viscous forces is demonstrated, and the effect of surface tension, air drag and non-isothermal flow is discussed briefly.