Turning to the variation shown in FIG 10, this embodiment is similar to that shown in FIG 7 in that the outlet apertures 152 are formed about {TAIL ~ the circumference} of {HEAD ~ the secondary inner shell} 40 and are spaced a short distance from its first end 42 
Turning to the variation shown in FIG 10 , this embodiment is similar to that shown in FIG 7 in that the outlet apertures 152 are formed about { TAIL ~ the circumference } of { HEAD ~ the secondary inner shell } 40 and are spaced a short distance from its first end 42
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH