As shown best in FIGS 1 and 2, cylinder 1 is in the form of {TAIL ~ a cylindrical, substantially hollow housing} 2 which defines {HEAD ~ a central longitudinal axis} 3 about which cylinder 1 is rotated 
As shown best in FIGS 1 and 2 , cylinder 1 is in the form of { TAIL ~ a cylindrical , substantially hollow housing } 2 which defines { HEAD ~ a central longitudinal axis } 3 about which cylinder 1 is rotated
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH