My uncle did that when when starter solenoid failed on 1950's Ford tractor and he went to use jumper cables from the battery to the starter and forgot it was positive ground. Dad came flying across the field thinking someone had gotten shot or something.
If your really that desperate for a light then it would make more sense to me to yank a dome light or something out and use it.
I wonder if the graphite would make a good fire starter though.