Improvements in or relating to jet pumps

A jet pump consists of a central passageway (11) surrounded by an annular member (2) through which holes (10) are provided, both at an angle to the axis (24) of the passageway and at an angle to respective radial planes, so that when a fluid is ejected through the holes its momentum drives forward the material in the passageway thereby generating a pumping action. The pump has many uses including the transfer of fluids, suspensions of a solid in a fluid or granular solids; the mixing of a fluid with another substance; aeration; dilution. Two or more pumps may be used in parallel or series to provide an increased flow and/or head. By mounting two pumps back-to-back a backflushing facility is provided. A particular advantage of this type of pump is that, having no moving parts, it is suitable for location in inaccessible places such as submerged environments. Hence the discharge from a submerged pump may act as a source of motive power to move a structure attached thereto such as a stiffer in a large tank or a water borne craft.