Abstract: In a jet pump suitable for pumping liquids, gases, or particulate solids, the primary and secondary flows both pass through the pump in-line, i.e. in the same axial direction. This is achieved by mounting the nozzle head (from which the primary flow issues) at one end of a streamlined body which is suitably supported in the mixing chamber. The suction hose opens directly onto the other end of the body. The whole of the primary flow passes through the streamlined body, so that the secondary flow is sucked over the streamlined body and entrained by the primary flow.The primary flow may issue from a single nozzle at the downstream end of the streamlined body. Alternatively several jets may issue from a ring of nozzles and also from a further nozzle in the center of the ring, all the nozzles being so angled that several jets converge downstream of the nozzle head.