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Abstract
A yarn may be drafted from a large mass of fibres by using twist to supply the nip force to select fibre leading ends. An account is given of an experimental machine using this principle in which withdrawal tension in the yarn was used to control the amount of twist being inserted. The coefficients of variation of the mass per unit length of a series of yarns produced by this machine are compared with a minimum value calculated assuming perfect operation. Some possible reasons for the shortcomings in levelness are discussed. Experiments in which the forces necessary to extract single fibres and groups of fibres from large masses are described and their relevance to tension control of twist is discussed.