What did a jacob’s staff do for the 16th century navigation

Jacob's Staff was invented in the 13th century as an aid in finding heights and distances. It was not until the 15th century that the German scientist Johannes Mueller popularized the instrument.

This was the age when the Europeans began exploring beyond the Mediterranean Sea. They needed better navigation tools so they could more accurately determine their latitude and longitude, and not run into too many rocks.

Jacob's Staff was shaped like a cross-bow. It had a main rod with a scale, and several cross pieces which were used to determine angles, either from the horizontal looking up (the "angle of elevation"), or perhaps between 2 objects.

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answer

the statement that best describes president carter’s attempt to free the hostages in iran is c. all of the attempts failed.

explanation

the operation eagle claw conducted by the united states armed forces was a failed mission which aimed to rescue 52 americans captured as hostages in the american embassy, tehran on 24/4/1980.the mission was authorized by president jimmy carter. the failures included;   obstacles in operation that included operational conditions challenges caused by sandstorms, hydraulic problems of one the helicopters and , mechanical failure of another helicopter that was identified as a cracked rotor blade and the crashing of another helicopter during mission abortion causing death of 8 service persons.