The other end of the arch block is supported on {HEAD ~ a spring} in {TAIL ~ a blind hole} in the arched notch 
in
The other end of the arch block is supported on { HEAD ~ a spring } in { TAIL ~ a blind hole } in the arched notch
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH