Thus exactly the same distribution results as if the particles had been projected from a point source at the origin. This has an application in spraying. Consider two sprays of the common revolving nozzle type, mounted so that the centres of revolution may be considered coincident, with the nozzles revolving in opposite directions and emitting thin jets of the spraying fluid horizontally perpendicular to the revolving arms (Figure 1). The angular velocities of the arms are equalb and the amounts of fluid ejected per second. Take the origin at the common centre of revolution, and axes parallel