In the 18th century John Harrison solved the problem of determining longitude at sea using what instrument?

Question

What is a navigation instrument used until the 18th century to measure the angles between heavenly bodies, or between them and the horizon?

Answer 1

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The British Parliament offered £20,000 (comparable to £2.87 million / €3.65 million / $4.72 million now) for the solution. He received some money (£8,750) from Parliament for his work, but not the award.