When it is desired to improve the performance of a given shape of insulator by the incorporation of {TAIL ~ barriers} in accordance with the present invention, {HEAD ~ such barriers} may in some cases conveniently be incorporated initially, during the construction of the insulator 
When it is desired to improve the performance of a given shape of insulator by the incorporation of { TAIL ~ barriers } in accordance with the present invention , { HEAD ~ such barriers } may in some cases conveniently be incorporated initially , during the construction of the insulator
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH 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