About 22% of the energy used in the U.S. comes from natural gas. There are about 300,000 miles of natural gas pipelines in the lower 48 states and 425,000 gas producing wells. The history of natural gas.
thru-hole. A circuit board packaging technique in which the leads (pins) on discrete components and chips are inserted through holes in the printed circuit board and soldered from beneath.
The term 'hole in the wall' is used to describe a house, or a restuarant or a shop that is is small, dark, sub-standard, or off the beaten path, and just not very nice. In this case it probably refers to how the children lived before they came to live in the camps.