Amos 7:8 “And the LORD said unto me, Amos, what seest thou? And I said, A plumbline. Then said the Lord, Behold, I will set a plumbline in the midst of my people Israel: I will not again pass by them any more:” This is a tool rarely used in building today. I’m not sure if kids of this age have ever heard of a plumb bob. It is used for a straight vertical line. It is used much in laying concrete block or rock walls. In early years it was used in place of a level. My grandfather called it a spirit level, a name from years gone by. I assume it was because they used ethanol instead of water in the bubble glass so that it wouldn’t freeze and break.