Workers in the field of continuous combustion have long been aware of the importance of the part played by the aerodynamic factors in the satisfactory operation of combustion systems. Although only part of a complex process, the air flow in a combustion system can, to some extent, be studied as an isolated individual factor, without the complications of fuel injection and heat release. This may appear to involve a rather long step from reality, but observations of the basic “cold” flow conditions in such a system can provide a valuable basis for the prediction of the effects of variations in the equipment, particularly in systems conforming to a particular type.