Hand (unit) radix numbering system, where a hand is four inches. The hand, sometimes also called a handbreadth or handsbreadth, is an anthropic unit, originally based on the breadth of a male human hand, either with or without the thumb, or on the height of a clenched fist. On surviving Ancient Egyptian cubit-rods, the royal cubit is divided into seven palms of four digits or fingers each. Five digits are equal to a hand, with thumb; and six to a closed fist. The royal cubit measured approximately 525 mm, so the length of the ancient Egyptian hand was about 94 mm. In
Hand-Held Maneuvering Unit use his HHMU on Gemini 11, because his EVA had to be cut short when he became fatigued. Hand-Held Maneuvering Unit The Hand-Held Maneuvering Unit (HHMU), also known as the maneuvering gun, or informally as "the zip gun", was used by astronaut Ed White in the first American "spacewalk" (extra-vehicular activity, EVA), on Gemini 4, June 3, 1965. Different models of HHMU were present on Gemini 4, 8, 10, and 11, but were only used on Gemini 4 and 10. It was also used aboard Skylab. Astronauts described the gun as easier to use than other methods of maneuvering during