A summary of developments was made in the last review report on rubber mixing (355) and mention was made of the development of rubber mixers by Fernley H. Banbury. One rotor design which was developed in the Werner, Pfleiderer and Perkins company in Peterborough should, however, perhaps be given more prominence than it so far has. That design was illustrated in a British patent (a.1, Figure 1) and was slightly modified in an American patent taken out in 1915 by J.E. Pointon (a.2, Figure 2). Examination of the sketches of these rotors in the patents indicates a rotor profile remarkably similar to that used by Banbury in his 1916 patent for the Banbury mixer (a.3), and in the case of the British patent featuring the same method of driving compound to the middle of the mixing chamber, albeit with a single wing. It is recorded (a.4) that Banbury worked in Peterborough at around the time when Pointon was developing his ideas, and probably saw the advantages of that rotor profile and the way the Pointon rotor moved material around the mixing chamber. The principle of sweeping rubber from one end of the mixing chamber to the other, and returning it back using a second rotor, as indicated in the US patent, is the same as that used in the original intermix rotor of 1934. This same idea of a long, sweeping wing to drive material along the length of the mixing chamber could be said to have been incorporated in...