Third and final article in W. H. Booth's series on the cotton spinning factory, published in Cassier's Magazine. It describes the spinning operation on throstle, ring frame and self-acting mule, with notes on their history (Arkwright, Crompton, Roberts), twist calculations and mule action. It then gives machinery lists for standard mills (Tables I and II), floor plans and descriptions of several Lancashire mills (Stanhill, Cairo, Curzon, Broadstone, Kearsley, Imperial), and notes on construction, engines, shafting and fire protection. Illustrated with photographs of machines by Howard & Bullough, Platt Bros., Asa Lees and Dobson & Barlow.