Dip Stick Level Measurement

Flexible lines fitted with end weights called chains or lead lines have been used for centuries by seafarinng men to gauge the depth of water under their ships. Steel tape having plump bob- like weights and stored conveniently in a reel are still used extensively for measuring level in fuel oil bunkers and petroleum storage tanks.

Though crude as this methods seems, it is accurate to about 0.1% with ranges up to about 20 feet.