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.
A blue hole is a cave (inland) or underwater sinkhole. They are also called vertical caves. There are many different blue holes located around the world, typically in low-lying coastal regions. The best known examples can be found in Belize, the Bahamas, Guam, Australia (in the Great Barrier Reef), and Egypt (in the Red Sea).