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In recent years attention has been given to the momentum of sprays particularly in scaling problems for systems where jets and sprays are used, e.g. furnaces. Little is known, however, of how momentum is distributed within a spray between the drops and the entrained air, and how this distribution varies with the distance from the nozzle. This information would be useful in a number of cases where sprays and dispersions are involved in processes of heat and mass transfer. In general, the well-known aerodynamic laws governing the motion of particles cannot be applied to estimate this distribution, firstly, beceuse of interference between particles and secondly, because of deformation of liquid drops in flight. During the course of work on the extinction of fires with water sprays from pressure nozzles, however, methods were developed for measuring certain spray properties from which a useful picture of aerodynamic conditions within a spray could be obtained. In this paper a description of those methods is given and their use illustrated.