whereby the expansion of {HEAD ~ said pressure} transmitting medium by said driving means is concentrated at said elastic wall portion, to move said elastic wall portion to drive said {TAIL ~ printing element} 
whereby the expansion of { HEAD ~ said pressure } transmitting medium by said driving means is concentrated at said elastic wall portion , to move said elastic wall portion to drive said { TAIL ~ printing element }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD 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