The incandescent filament lamps are electrically connected in {HEAD ~ series} and powered by {TAIL ~ an AC power supply} 
The incandescent filament lamps are electrically connected in { HEAD ~ series } and powered by { TAIL ~ an AC power supply }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL