An ell (from Proto-Germanic *alinō, cognate with Latin ulna) is a unit of measurement, originally a cubit, i.e., approximating the length of a man's arm from the elbow ("elbow" means the bend or bow of the ell or arm) to the tip of the middle finger, or about 18 inches (457 mm); in later usage, any of several longer units.

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A cable length or length of cable is a nautical unit of measure equal to one tenth of a nautical mile or approximately 100 fathoms. The unit is named after the length of a ship's anchor cable in the Age of Sail. The definition varies:

• International:  ¹⁄₁₀ nautical mile, or 185.2 m
• Imperial (Admiralty):  ¹⁄₁₀ Admiralty mile, or 608 ft (185.32 m), about 101 fathoms
  • The traditional British fathom varied from 5½ feet to 7 feet in the Merchant Navy.
• U.S. customary (US Navy): 120 fathoms (720 feet, 219.456 m)

conversion table