At the top of a drilling rig derrick is the crown block (a series of sheaves) surrounded by a small platform called the water table. In the drilling business a new hand is called a "worm" out on the rig. Back in my roughnecking days, we would send a worm climbing the derrick with a five gallon bucket of water for the "water table".

Yes, I did climb the derrick doing such a thing when I was a worm at 16 years old. Some of you oilfield folks know what I'm talking about.