present invention is shown in fig9 a and 9b as may be evidenced from fig9 b this embodiment has a rectangularly shaped outlet and housing and has its greatest applicability in cramped space quarters such as are found in shallow seam coal mines the air pumping apparatus 76 generally includes two converging wall portions 78 and two diverging wall portions 80 located at the wide ends of wall portions 78 and 80 respectively are an inlet 82 and an outlet 84 wall portions 78 and 80 are formed as the shortened walls of a housing having an hourglass configuration with a rectangular cross section when the section is taken through a plane normal to a longitudinal axis or center line 86 of the housing the remaining lengthened wall portions of the 34 rectangle 34 are walls 88 and 90 as shown in fig9 b positioned within the converging chamber 92 formed by the wall portions 78 and directed toward the diverging chamber 94 and formed as a mixing chamber is a spray nozzle 96 the spray nozzle 96 is fed pressurized water through appropriate piping 98 or the like nozzle 96 in much the same manner as nozzle 66 in fig8 sprays a divergent solid cone of water 100 toward the outlet 84.